U.S. patent application number 12/921777 was filed with the patent office on 2011-02-24 for device for launching a projectile or a launch object in general.
Invention is credited to Pasquale Stanziale.
Application Number | 20110041820 12/921777 |
Document ID | / |
Family ID | 40293175 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110041820 |
Kind Code |
A1 |
Stanziale; Pasquale |
February 24, 2011 |
DEVICE FOR LAUNCHING A PROJECTILE OR A LAUNCH OBJECT IN GENERAL
Abstract
A device (1) for launching a projectile, comprising: a stock
(2); at least two bending members (10) associated to said stock (2)
on opposite sides thereof; tensioning means (323) of said bending
members (10), comprising at least two cams (323) arranged on
opposite sides of the stock (2), each of which is pivoted at a
respective first axis of rotation (33) and is associated to at
least one corresponding bending member (10); pushing means (30) of
said projectile apt to cooperate with said bending members (10)
comprising at least two pushing arms (32) arranged on opposite
sides of the stock (2) and connected to each other through a
flexible pushing member (31) wherein each of said pushing arms (32)
is pivoted at a respective axis of rotation (33) and is apt to
support a portion of said flexible pushing member (31), each of
said pushing arms (32) being operatively connected to a respective
cam (323), wherein said device (1) further comprises a flexible
force member (37) for commanding a rotation of a pushing arm (32),
and two pairs of pulleys (145, 146) arranged on opposite sides of
the stock (2), wherein each pair comprises a first pulley (145)
interposed between a respective pushing arm (32).
Inventors: |
Stanziale; Pasquale; (Ravina
(Trento), IT) |
Correspondence
Address: |
Steinfl & Bruno
301 N Lake Ave Ste 810
Pasadena
CA
91101
US
|
Family ID: |
40293175 |
Appl. No.: |
12/921777 |
Filed: |
March 9, 2009 |
PCT Filed: |
March 9, 2009 |
PCT NO: |
PCT/IB09/50983 |
371 Date: |
September 9, 2010 |
Current U.S.
Class: |
124/25 |
Current CPC
Class: |
F41B 5/123 20130101;
F41B 5/105 20130101; F41B 5/1469 20130101 |
Class at
Publication: |
124/25 |
International
Class: |
F41B 5/12 20060101
F41B005/12; F41B 5/14 20060101 F41B005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 10, 2008 |
IT |
RM2008A000130 |
Oct 3, 2008 |
IB |
PCT/IB08/54053 |
Claims
1. A device for launching a projectile or a launch object in
general, comprising: a stock having a longitudinal development
direction between a rear or proximal end and a front or distal end,
at least two bending members associated to said stock on opposite
sides of it and having a preferential development direction, said
bending members being apt to be subjected to flexing in order to
accumulate and supply energy usable to launch said projectile, and
released in a rest condition, tensioning means of said bending
members, pushing means of said projectile apt to cooperate with
said bending members, wherein said tensioning means comprise at
least two cams arranged on opposite sides of the stock, each of
which is pivoted at a respective first axis of rotation and is
associated to at least one corresponding bending member, so that an
angular displacement of a cam around said first axis of rotation
determines a flexing action on said at least one corresponding
bending member, and said pushing means comprise at least two
pushing arms arranged on opposite sides of the stock and connected
to each other through a flexible pushing member for pushing said
projectile, wherein each of said pushing arms is pivoted at a
respective axis of rotation and is apt to support a portion of said
flexible pushing member, each of said pushing arms being
operatively connected to a respective cam, so that a rotation of
each pushing arm in a first rotation direction determines a flexing
of said bending members by means of the respective cam during a
loading phase of the device and that, during a launch phase of said
projectile, a return of the bending members towards said rest
condition determines, by means of the cam, a rotation in the
opposite direction of each pushing arm, wherein said device further
comprises a flexible force member for commanding a rotation of a
pushing arm during said loading phase, and two pairs of pulleys
arranged on opposite sides of the stock, wherein each pair
comprises a first pulley interposed between a respective pushing
arm and said flexible pushing member, and a second pulley
interposed between the respective pushing arm and said flexible
force member, said first pulley being rotatably connected to said
second pulley for a coordinated rotation thereof around respective
axes of rotation, so that in said rest condition the flexible
pushing member is partially wound on the first pulley, and that
during said loading phase the flexible pushing member gets unwound
from the first pulley and the flexible force member gets wound on
the second pulley, and that during said launch phase the flexible
pushing member gets wound on the first pulley and the flexible
force member gets unwound from the second pulley.
2. The device according to claim 1, wherein said pushing arms are
rotatable between a first maximum loading position, corresponding
to a maximum flexing of the bending members, and a second maximum
discharge position, between said first maximum loading position and
said second maximum discharge position there being a neutral
position at which said bending members are in said rest condition
not presenting accumulated elastic energy.
3. The device according to claim 2, wherein in said first maximum
loading position the pushing arms are rotated towards said rear or
proximal end of the stock, and in said second maximum discharge
position the pushing arms are rotated in the direction of said
front end of the stock.
4. The device according to claim 1, wherein a portion of each of
said bending members is associated idle to a portion of a
respective cam, so as to allow said portion of bending member to
make a translation movement together with said portion of cam, said
translation movement taking place along a direction substantially
orthogonal to said preferential development direction of said
bending member.
5. The device according to claim 4, wherein said portion of a
respective cam is a slot in said respective cam at the respective
first axis of rotation.
6. The device according to claim 5, comprising a connection element
positioned idle in said slot, said connection element comprising a
connection member apt to move said portion of said at least one
bending member.
7. The device according to claim 6, wherein said connection element
comprises two of said connection members, positioned symmetrically
and connected to each other by a collar which is engaged in said
slot of a respective cam, each of said connection members being apt
to move said portion of a respective bending member.
8. The device according to claim 1, further comprising retaining
members for retaining said bending members, arranged on opposite
side of the stock, each retaining member being pivoted to said
stock and associated to at least one bending members.
9. The device according to claim 6, further comprising retaining
members for retaining said bending members, arranged on opposite
sides of the stock, each retaining member being pivoted to said
stock and associated to at least one bending members, wherein each
retaining member is associated to a respective connection
member.
10. The device according to claim 1, wherein each of said pushing
arms forms a single part with a respective cam and the axis of
rotation of said pushing arm is coincident with said first axis of
rotation of said respective cam.
11. The device according to claim 1, wherein each of said pushing
arms is connected to a respective cam by at least one connecting
rod pivoted to said pushing arm and to said cam.
12. The device according to claim 1, further comprising a pivot
body of determined axis associated to the stock and positioned
between the opposing cams, wherein a first of said cams and a
second of said cams are hinged on said pivot body at a second axis
of rotation.
13. The device according to claim 12, further comprising a slide
associated to the stock and positioned between the opposing cams,
said slide comprising said pivot body and being apt to slide in
said stock substantially parallel to said longitudinal development
direction.
14. The device according to claim 1, wherein said first pulley
and/or said second pulley has/have an eccentric profile with
respect to a respective axis of rotation.
15. The device according to claim 1, wherein said first pulley and
said second pulley supported by a same pushing arm are apt to
rotate jointly around a same axis of rotation, said first pulley
and second pulley being jointly associated to a common pivot.
16. The device according to claim 1, wherein said first pulley and
said second pulley supported by a same pushing arm are apt to
rotate around distinct axis of rotation, said first pulley being
jointly associated to a respective first pivot and said second
pulley being jointly associated to a respective second pivot,
wherein said coordinated rotation between said first pulley and
said second pulley is obtained by means of a wheel jointly rotating
with one of said first pivot and second pivot, and mating the other
of said first pivot and second pivot.
17. The device according to claim 16, wherein said mating is
obtained by means of toothing or by means of friction coupling.
18. The device according to claim 1, wherein a first length of said
flexible force member is associated to a respective second pulley
and a second length of said flexible force member is associated to
a tightener element secured to the stock.
19. The device according to claim 18, wherein said tightener
element is a frame.
20. The device according to claim 1, comprising retaining members
for retaining said bending members, arranged on opposite side of
the stock, each retaining member being pivoted to said stock and
associated to at least one bending members, and further comprising
two flexible force members arranged on opposite sides of said
stock, wherein a flexible force member has a first length
associated to a respective second pulley and a second length
associated to a side appendix of a respective retaining member.
21. The device according to claim 1, comprising retaining members
for retaining said bending members, arranged on opposite sides of
the stock, each retaining member being pivoted to said stock and
associated to at least one bending members, and further comprising
two flexible force members arranged on opposite sides of said stock
and a return pulley pivoted to a side appendix of a respective
retaining member, wherein a flexible force member has a first
length associated to a respective second pulley, a second length
associated to a respective pushing arm, and a intermediate length
interposed between said first length and second length and going
around said return pulley, said return pulley acting as a tightener
element of said flexible force member.
22. The device according to claim 1, further comprising two
flexible force members arranged on opposite sides of said stock and
further comprising a return pulley pivoted to said stock, wherein a
flexible force member has a first length associated to a respective
second pulley, a second length associated to a respective pushing
arm, and a intermediate length interposed between said first length
and second length and going around said return pulley, said return
pulley acting as a tightener element of said flexible force
member.
23. The device according to claim 1, wherein said bending members
are arranged so that said preferential development direction is
substantially parallel to said longitudinal development direction
of said stock.
24. The device according to claim 23, wherein said bending members
are positioned substantially adjacent to said stock.
25. The device according to claim 1, wherein said at least two
bending members, said at least two cams and said at least two
pushing arms are arranged in a manner substantially symmetrical
with respect to said stock.
26. The device according to claim 1, comprising, on each side of
said stock, at least two bending members opposite to each other
with respect to a plane on which said cams lie, forming, overall, a
group of at least four bending members symmetrical with respect to
the longitudinal development direction of the stock.
27. The device according to claim 1, further comprising contrast
means associated to said stock, and operatively connected to said
cams.
28. The device according to claim 2, further comprising contrast
means associated to said stock and operatively connected to said
cams, wherein said contrast means are loaded so as to exert a force
on said cams only when said pushing arms are beyond said neutral
position towards said second maximum discharge position.
29. The device according to claim 27, further comprising elastic
means apt to bring back said pushing arms towards said neutral
position.
30. The device according to claim 13, further comprising contrast
means associated to said stock, and operatively connected to said
cams, wherein said contrast means and/or said elastic means are
operatively connected to said slide.
31. The device according to claim 1, further comprising auxiliary
pushing means including at least one elastic member apt to
accumulate energy during said loading phase of the device and apt
to supply said energy to said pushing means during said launch
phase of said projectile.
32. The device according to claim 1, comprising associating means
of at least one of said bending members to said stock, wherein said
associating means are apt to prevent a translation of a tract of
said at least one bending member in a direction orthogonal to said
preferential development direction, and to allow said tract a
flexing movement, and/or an angular displacement with respect to
said stock, and/or a translation in said preferential development
direction of said at least one bending member.
33. The device according to claim 32, wherein said associating
means are apt to prevent said translation in said orthogonal
direction to a first tract and to a second tract of said at least
one bending member, wherein said first tract and second tract
correspond to end tracts thereof.
34. The device according to claim 1, comprising associating means
of at least one of said bending members to said stock, wherein said
associating means are apt to join a tract of said at least one
bending member to the stock in such a way as to prevent said tract
both a translation with respect to the stock in said preferential
development direction and in a direction orthogonal to said
preferential development direction, and an angular displacement
with respect to the stock.
35. The device according to claim 1, wherein said device is a
crossbow.
Description
[0001] The present disclosure refers to a device for launching a
projectile, or an arrow, or a bolt, or a launch object in general.
More specifically, it refers to a perfected type of archery
crossbow.
[0002] Several types of devices for launching a projectile are
already known, both for sports and amateur uses, and for
professional uses. Among these, there are, in particular,
crossbows, generally consisting of a bow (in wood, metal, plastic
or composite material, e.g. including glass or carbon fiber) apt to
accumulate elastic energy and return it to the projectile to be
launched, a propulsive wire for pushing the projectile, a fastening
system to keep said wire in the loaded position and then release
it, a stock secured to said bow and comprising a support-guide for
the projectile.
[0003] The modern devices for launching a projectile usually have a
bow divided into two bending members (i.e. flexing members, also
called limbs) which are identical (left and right) and secured to a
central handle member (also called riser) or to the stock of the
device.
[0004] In some embodiments (e.g. U.S. Pat. No. 3,854,467; U.S. Pat.
No. 3,923,035; U.S. Pat. No. 3,987,777), there are pulleys pivoted
to the free ends of the bending members and pulleys pivoted to a
central member; the pulleys include tracks on which a propulsive
wire is partially wound. Under the most common arrangement, a
propulsive wire is connected to one pulley and to its symmetrically
opposite one on the other side; each one of said pulleys is
integral to a smaller pulley, which holds one end of another wire,
whose other end is connected to the opposite limb. Some of the
pulleys may have an eccentric profile.
[0005] The traction of the propulsive wire turns the pulleys,
unwinding the propulsive wire from some pulleys, while at the same
time the other wires are wound around other pulleys; this causes
the flexing of the bending members and the accumulation of elastic
energy. Thanks to an adequate profiling of the pulley tracks and an
appropriate eccentricity of the same, in these devices it is
possible to reduce the maximum force which must be exerted by the
user during the loading of the device and to increase the ratio
between the stroke of the projectile (also called "draw length")
and the movement of the ends of the bending members.
[0006] Other embodiments of devices for the launching of
projectiles comprising pulleys or the like for a similar purpose
are disclosed, for example, in U.S. Pat. No. 5,388,564, U.S. Pat.
No. 5,499,618, U.S. Pat. No. 5,967,132. Embodiments of a crossbow
comprising pulleys are disclosed, for example, in U.S. Pat. No.
5,630,405 and U.S. Pat. No. 6,155,243.
[0007] One of the main disadvantages of the devices of known art
and, in particular, of crossbows of known art, is that, during the
launch phase, the bending members, the propulsive wire and any
pulleys arrive at the end of the stroke with a high residual
kinetic energy, proportional to the masses in movement; because of
the very structure of the device, this energy must be dissipated in
a very short space or even in no space, as the components in motion
have already reached the end of their possible stroke. The stopping
of the components in motion after the launch is, therefore, quite
sudden and subjects the entire device to an end-of-stroke shock
which involves very high stresses, discharging the residual energy
on the wires and stressing the pivots of the pulleys and the
bending members. Indeed, in the case of dry firing (that is, no
projectile is fired), there is no transfer of energy to a free mass
and the stresses may be so high as to break the device.
[0008] This dictates structural constraints in the dimensioning of
the device, imposes practical limits on the projectile mass that
can be launched safely and imposes very high levels of attention
and expertise on the user, who could damage the crossbow or even
get injured in case of dry firing or of using too light a
projectile.
[0009] In the case of said more advanced devices, the problem is
actually accentuated by the presence of the pulleys at the ends of
the bending members, as this considerably increases the masses, the
kinetic energy and the moments of inertia in play. In addition, the
sudden stop at the end of the stroke is the main cause of the noise
produced during the use of these devices for launching a
projectile.
[0010] Another disadvantage of the devices of known art is the fact
that, even when the device is in the initial position, the bending
members are in a tensioned state; among other things, this makes it
necessary to use specific tools, such as a press, in order to carry
out maintenance operations such as the replacement of the
propulsive wire.
[0011] Finally, it must be noted that possible differences, even
slight ones, in the elastic characteristics of the right and left
bending members may be the cause of asymmetries in the thrust
exercised on the projectile and, therefore, compromise the launch
accuracy. On the other hand, the pulleys do not manage to
compensate for any such differences in the elastic characteristics
of the bending members.
[0012] Moreover, the crossbows of known art usually take the form
of a device which allows little or no possibility of adapting it to
the requirements of the user: once a crossbow of known art has been
built to certain specifications, the maximum power or the force
required for the loading are substantially fixed and can no longer
be varied, except with laborious replacements of components which,
in any case, are beyond the common user's skill. These
interventions, in fact, are dangerous and also void the warranty
provided by the manufacturer.
[0013] The present disclosure, therefore, moves from the position
of the technical problem of providing a device for launching a
projectile or a launch object in general which makes it possible to
overcome at least one of the drawbacks specified above with
reference to the known art, and to gain further advantages.
[0014] As defined in independent claim 1, this is obtained by
providing a device for launching a projectile or a launch object in
general, comprising: [0015] a stock having a longitudinal
development direction between a rear or proximal end and a front or
distal end, [0016] at least two bending members associated to said
stock on opposite sides of it and having a preferential development
direction, said bending members being apt to be subjected to
flexing in order to accumulate and supply energy usable to launch
said projectile, and released in a rest condition, [0017]
tensioning means of said bending members, [0018] pushing means of
said projectile apt to cooperate with said bending members,
[0019] wherein said tensioning means comprise at least two cams
arranged on opposite sides of the stock, each of which is pivoted
at a respective first axis of rotation and is associated to at
least one corresponding bending member, so that an angular
displacement of a cam around said first axis of rotation determines
a flexing action on said at least one corresponding bending
member,
[0020] and said pushing means comprise at least two pushing arms
arranged on opposite sides of the stock and connected to each other
through a flexible pushing member for pushing said projectile,
[0021] wherein each of said pushing arms is pivoted at a respective
axis of rotation and is apt to support a portion of said flexible
pushing member, each of said pushing arms being operatively
connected to a respective cam, so that a rotation of each pushing
arm in a first rotation direction determines a flexing of said
bending members by means of the respective cam during a loading
phase of the device and that, during a launch phase of said
projectile, a return of the bending members towards said rest
condition determines, by means of the cam, a rotation in the
opposite direction of each pushing arm,
[0022] wherein said device further comprises a flexible force
member for commanding a rotation of a pushing arm during said
loading phase, and two pairs of pulleys arranged on opposite sides
of the stock, wherein each pair comprises a first pulley interposed
between a respective pushing arm and said flexible pushing member,
and a second pulley interposed between the respective pushing arm
and said flexible force member, said first pulley being rotatably
connected to said second pulley for a coordinated rotation thereof
around respective axes of rotation, so that in said rest condition
the flexible pushing member is partially wound on the first pulley,
and that during said loading phase the flexible pushing member gets
unwound from the first pulley and the flexible force member gets
wound on the second pulley, and that during said launch phase the
flexible pushing member gets wound on the first pulley and the
flexible force member gets unwound from the second pulley.
[0023] Secondary characteristics of the subject of the present
disclosure are defined in the corresponding dependent claims.
[0024] The subject of the present disclosure provides some
significant advantages.
[0025] A main advantage lies in that the device permits a reduction
in the stresses acting on the structure in the end-of-stroke
arrest, thanks to the gradual absorption of the inertia and kinetic
energy of the parts in movement in a braking run which follows the
propulsive run. Furthermore this braking run is especially long as
can be seen from the drawings. Also the braking run does not cut
short the useful run of the limbs or bending members, for example
by elastically intercepting the propulsive wire some distance
before their neutral position as conceivable in devices of known
art, that is, while they are still partially under tension; on the
contrary, the braking run intervenes when the bending members have
exhausted all the stored energy and when they have crossed the
neutral, zero energy state while flexing in the opposite direction.
The device can thus handle higher energies while also featuring
smoother and more silent action, and higher safety levels for the
user particularly in case of dry firing, compared to known-art
devices.
[0026] A second advantage lies in that the device makes it possible
to load higher energies compared to known-art devices. In fact the
use of a solid body (i.e., said cams) as the primary mover acting
on the bending members (rather than a wire) allows for the
application of greater force and the use of more rigid bending
members, thereby increasing the maximum energy that can be
transmitted.
[0027] A third advantage is that the increment of the length of
wire (i.e., of said flexible force member) to be wound on the force
pulleys (i.e., said second pulleys), consequent chiefly to them
being attached to levers (i.e., said pushing arms) and augmentable
in various ways which will be shown, widens the scope for
force-draw curve reshaping compared to known-art devices. In
particular it is considered desirable to obtain a force-draw curve
as flat as possible along most of its length so as to minimize the
maximum effort that the user has to put in loading the device
(commonly referred to as draw weight) in relation to the draw
length and, since this last is essentially limited for devices of
practical size, in relation to the energy stored.
[0028] A fourth advantage lies in that the device makes it possible
to vary the specific use characteristics and it has a simpler
maintenance. In fact said bending members are released in the rest
condition, i.e. they do not present accumulated elastic energy and
are non-deformed, so they can easily and safely be replaced with
other bending members of same or different characteristics. Also
the bending members do not present the risk of seeing their
performance degraded in warmer storing conditions.
[0029] Another advantage lies in that said device makes it possible
to synchronize the rotation of the left and right pushing means or
pushing arms, in order to compensate for asymmetries in the elastic
properties of left and right bending members. This determines a
uniform distribution of the force acting on the projectile during
the launch phase, eliminating the components of the acting force
which are orthogonal to the launch direction, which benefits the
launch accuracy.
[0030] A further advantage lies in that the device is of more
limited lateral dimensions since the bending members are oriented
substantially parallel to each other and to the stock and they lie
close to it, while the externally protruding pushing arms need not
extend much as the distance multiplication burden lies mostly with
the pulleys.
[0031] In an embodiment, the pushing arms are rotatable between a
first position of maximum loading and a second position of maximum
discharge. Between said first and second positions, there is a
neutral position at which the bending members do not present
accumulated elastic energy. In particular, in said first position
of maximum loading the pushing arms are rotated towards the
proximal end of the stock, and in said second position of maximum
discharge they are rotated towards the distal end of the stock.
[0032] To be more specific, said second position corresponds to the
maximum advance of the pushing arms towards the distal end, in the
braking stroke or run after the launch stroke, where with launch
stroke it is meant the run of the pushing arms between said first
position of maximum loading and said neutral position, while with
braking stroke it is meant the run of the pushing arms between said
neutral position and said second maximum discharge position.
[0033] Therefore, in the loaded device, the bending members are
initially in a bent or flexed configuration; during the launch
phase, the bending members gradually reduce the flexing, they pass
the rest position (corresponding to said neutral position) and
continue their movement by flexing in the opposite direction, until
they get to a configuration of maximum counter-flexing
corresponding to said second position of maximum discharge. One
advantage of this solution is that it allows for a gradual and
non-sudden stop of the components at the end of the launch phase,
thereby reducing the stresses at the end of the stroke and the risk
of damaging the device.
[0034] Contrast means, operating when the pushing arms are between
the neutral position and the position of maximum discharge may also
be optionally provided in order to cooperate with the bending
members in slowing down the moving parts.
[0035] In addition or in alternative to the contrast means, the
device may include auxiliary pushing means including at least one
elastic member apt to accumulate energy during the loading phase
and apt to supply energy to the pushing means during the launch
phase. This makes it possible to increase the power of the device
for a same overall dimensions.
[0036] In an embodiment, each pushing arm forms a single part with
a respective cam and the axis of rotation of the pushing arm is the
same as the axis of rotation of the respective cam. This solution
has the particular advantage of requiring a lower number of parts
and of being of simpler construction.
[0037] In an embodiment, each pushing arm is operatively connected
to a respective cam using at least one connecting rod pivoted to
the pushing arm and to the cam. This solution makes it possible to
reduce the maximum lateral dimensions of the device and allows for
greater design flexibility.
[0038] In an embodiment, the bending members are arranged so that
their preferential development direction is substantially parallel
to the longitudinal development direction of the stock. This
benefits the compactness of the device, reducing the lateral
dimensions. Preferably, the bending members are positioned close to
the stock.
[0039] In an embodiment, the bending members, the cams and the
pushing arms are arranged in a manner substantially symmetrical
with respect to the stock. This configuration is advantageous as
the symmetrical arrangement favors a symmetrical and balanced
distribution of the forces acting on the stock and the elimination
of the residual forces acting on the stock itself.
[0040] In an embodiment, the first axis of rotation of the cam
moves together with a portion of at least one bending member, in a
direction substantially orthogonal to the development direction of
the bending member. More specifically, each cam is pivoted using a
connection element comprising a first portion which is housed idle
in a slot of the cam and at least one other portion which is
associated to a tract of a corresponding bending member.
[0041] In an embodiment, at least one retaining member is provided
on each side of the stock, hinged on it, with the purpose of
holding a portion of said connection element so as to guide it and
constrain it along its movement. In this case the pushing arm and
said retaining member rotate in a coordinated fashion.
[0042] In an embodiment the device further comprises associating
means, or supports, of said bending members to the stock; the
associating means are apt to prevent a translation of a first tract
of a bending member, for instance an end of it, in a direction
orthogonal to the preferential development direction, and to allow
said first tract a flexing movement, and/or an angular displacement
with respect to the stock, and/or a translation in the preferential
development direction of the bending member. To be more specific,
said associating means are positioned at the two ends of a bending
member.
[0043] In an embodiment, a first cam and a second cam opposite
thereto are hinged on a pivot body associated to the stock and
positioned between the opposing cams; the axis of the pivot body
defines a second axis of rotation of said cams.
[0044] In an embodiment, a slide is positioned between one cam and
the respective symmetrical cam, and comprises the pivot body; the
slide can run along the device stock in a direction parallel to the
longitudinal development direction of the stock. So, the movement
of each cam is synchronized with that of the respective cam
positioned symmetrically. This makes for a uniform pull on the
propulsive flexible member.
[0045] In an embodiment each pushing arm supports a first pulley
which holds one end of a propulsive flexible pushing member with
the other end held by the symmetrically opposite pulley on the
other side.
[0046] In an embodiment, one flexible force member is provided,
having each end associated to a respective second pulley. In this
embodiment, the rotation of the second pulleys in a winding
direction causes the rotation of the pushing arms, which are being
pulled by the flexible force member. The flexible force member
passes from one side to the opposite side in a position suitable to
maximize the length to be wound. More specifically the flexible
force member is oriented in a direction approximately tangent to
the path described by the respective pushing arm. This reduces the
tension on the flexible force member and increases the eligible
size of the second pulleys, increasing the scope for force-draw
curve reshaping.
[0047] In an alternative embodiment, two flexible force members are
provided, one on each side of the stock, each one having a first
end associated to a respective second pulley and a second end
associated to a side appendix, for instance a lateral arm,
extending from a respective retaining member. In a preferred
embodiment, the pushing arm and the corresponding lateral arm
rotate in opposite directions moving one towards the other during
loading and away from each other during launch. Therefore, by
attaching one end of the flexible force member to the retaining
member, the length that is to be wound around the second pulley is
increased and the tension in the flexible force member is reduced,
so that the flexible force member can be thinner. This allows
greater design freedom for the second pulley, because it can now
have a larger maximum radius and a smaller minimum one.
Consequently, the eccentricity value of the second pulley can be
selected in a larger interval. This is beneficial since a larger
second pulley widens the scope for force-draw curve reshaping.
[0048] Moreover, in said embodiment, the retaining members
cooperate with the pushing arms in transmitting energy to and from
the bending members. Therefore, the overall pushing action is more
balanced and a better structural efficiency is achieved. For
instance, the pushing arms can be lighter, because they are
subjected to a lower stress.
[0049] In an embodiment, the first pulley and the second pulley on
the same pushing arm are associated to a same common pivot rotating
jointly with them. Therefore the first and the second pulleys have
the same axis of rotation and the same angular velocity. The
direction of rotation of a pair of pulleys may be either coherent
with the respective pushing arm (for instance, both clockwise, or
both counterclockwise), or opposite to the respective pushing arm
(one clockwise and the other counterclockwise), depending on which
side of the pulleys the flexible members are fastened to. The
rotation of the pulleys may perform a plurality of turns or
revolutions.
[0050] In an alternative embodiment, the first pulley and the
second pulley are pivoted at different axes of rotation; in fact
each pulley is jointly associated to a respective pivot, which is
rotatably associated to the pushing arm. The two pulleys are
operatively connected by means of a gearing for example with
toothed portions or frictionally coupled. This allows to reduce the
overall dimensions of the pulleys, to increase the draw length
(useful in particular when applied to a catapult), to widen design
freedom for obtaining the desired characteristics of the
device.
[0051] Further advantages, characteristics and the modes of
employment of the subject of the present disclosure will become
apparent from the following detailed descriptions of preferred
embodiments thereof, presented for exemplificative and not
limitative purposes.
[0052] It is however evident that each embodiment described in this
disclosure may present one or more of the advantages listed above;
in any case, it is not required that each embodiment presents at
the same time all the advantages listed.
[0053] Reference will be made to the figures of the attached
drawings, in which:
[0054] FIG. 1 shows a plan view of an embodiment of a crossbow
according to the known art;
[0055] FIG. 2A shows a perspective view of a first embodiment of a
device for launching a projectile according to the present
disclosure, in a first operative position;
[0056] FIG. 2B shows a perspective view of the device in FIG. 2A,
in a second operative position;
[0057] FIG. 2C shows a perspective view of the device in FIG. 2A,
in a third operative position;
[0058] FIG. 3 shows a perspective view of an enlarged detail of the
device in FIG. 2A, from which some components were removed;
[0059] FIG. 4 shows an exploded perspective view of a further
enlarged detail of the device in FIG. 2A;
[0060] FIG. 5 shows an enlarged front perspective view of the
device in FIG. 2A;
[0061] FIG. 6 shows an exploded perspective view of a further
enlarged detail of the device in FIG. 2A;
[0062] FIG. 7 shows an enlarged side perspective view of the device
in FIG. 2A;
[0063] FIG. 8 shows a perspective view of a further enlarged detail
of the device in FIG. 2A, from which some components were
removed;
[0064] FIG. 9 shows an exploded perspective view of a further
enlarged detail of the device in FIG. 2A;
[0065] FIG. 10 shows a perspective view of a further enlarged
detail of the device in FIG. 2A;
[0066] FIG. 11 shows an exploded perspective view of the detail in
FIG. 10;
[0067] FIG. 12 shows a perspective view of the device in FIG. 2A,
in a non-operative position;
[0068] FIG. 13 shows a perspective view of the detail of FIG. 10,
in a non-operative position;
[0069] FIG. 14A shows a perspective view of a second embodiment of
a device for launching a projectile according to the present
disclosure, in a first operative position;
[0070] FIG. 14B shows a perspective view of the device in FIG. 14A,
in a second operative position;
[0071] FIG. 14C shows a perspective view of the device in FIG. 14A,
in a third operative position;
[0072] FIG. 15 shows a perspective view of an enlarged detail of
the device in FIG. 14A, from which some components were
removed;
[0073] FIG. 16 shows an exploded perspective view of a further
enlarged detail of the device in FIG. 14A;
[0074] FIG. 17 shows a perspective view of a third embodiment of a
device for launching a projectile according to the present
disclosure, in a first operative position;
[0075] FIG. 18 shows an exploded perspective view of a further
enlarged detail of the device in FIG. 17;
[0076] FIG. 19 shows a perspective view of an enlarged detail of a
fourth embodiment of a device for launching a projectile according
to the present disclosure, in a first operative position.
[0077] An embodiment of an archery crossbow 1001 according to the
known art (U.S. Pat. No. 6,155,243) is shown in FIG. 1. The
crossbow 1001 has a stock 1002 with a butt 1003, two flexing or
bending members 1010 (or limbs) connected to said stock 1002, a
propulsive wire 1031 for pushing a projectile, a fasten and release
system (not shown, but located near the butt 1003) for holding and
releasing said propulsive wire 1031 in a launch position, a
shooting trigger (not shown). The free ends of the bending members
1010 support eccentric pulleys 1009, so that the propulsive wire
1031 passes at these and connects each pulley to the opposite
bending member. During the loading phase, shown in FIG. 1, the
propulsive wire 1031 is drawn towards the butt 1003, causing the
eccentric rotation of the pulleys 1009, the flexing of the bending
members 1010 and the accumulation of elastic energy in these.
During the launch phase, the same movements take place in the
opposite direction, with the transfer of energy to a projectile
(not shown) which slides in a suitable guide track 1008. This type
of known-art crossbow 1001 has the disadvantages already mentioned
above.
[0078] A first embodiment of a device for launching a projectile,
an arrow, a bolt, or a launch object in general, made according to
the present disclosure, is shown in FIGS. 2A to 13, where it is
indicated with the reference number 1.
[0079] Hereinafter, the present description will refer in
particular to archery crossbows; anyway, the same inventive
principles of the present disclosure can be similarly applied to
other launching devices, such as for example a bow or a
catapult.
[0080] The crossbow 1 comprises a stock 2 with a longitudinal
development direction 201, comprised between a rear or proximal end
205 and a front or distal end 206. The other components of the
crossbow 1 are associated to the stock 2. The portion of the stock
2 which is closest to a user during use, that is, the rear or
proximal end 205, comprises, in fact, a butt 3, a handle 4, a
fastening system 6 for reversibly fastening a flexible pushing
member 31 for pushing a projectile, a trigger 7 which makes it
possible to open the fastening system 6 in order to release the
flexible pushing member 31 when launching the projectile. The
components listed so far can be considered to be substantially
known-art components and, therefore, will not be described in
greater detail.
[0081] FIGS. 2A, 2B and 2C illustrate the crossbow 1 in three
different operative positions, which are respectively a neutral
(rest) condition, a loaded condition, and a maximum discharge
condition.
[0082] The crossbow 1 comprises at least two bending members 10, or
flexing members, which have an elongated shape along a preferential
development direction 202. For example, the bending members 10 have
a parallelepiped-like shape. They may be made of wood, metal,
fiberglass, plastic or composite material, e.g. including glass or
carbon fiber, or other suitable material.
[0083] The bending members 10 are suitable for being subjected to
bending or flexing in order to accumulate the elastic energy
required to launch the projectile, and to subsequently supply said
energy to the projectile during the launch. At the end of the
launch of the projectile, the bending members 10 are released in a
rest condition, in which they do not present accumulated elastic
energy and are non-deformed.
[0084] In the embodiment represented here, the bending members 10
are positioned substantially adjacent to the stock 2 and in a
symmetrical manner with respect to it; in the example, their
preferential development direction 202 is substantially parallel to
the longitudinal development direction 201 of the stock 2. To be
more specific, there are four bending members 10, as there are two
bending members 10 on each side of the stock 2.
[0085] The bending members 10 are associated to the stock 2 on
opposite sides of it. To be more specific, each bending member 10
is associated to the stock 2 through associating means positioned
near the proximal end 101 and the distal end 102 of the bending
member 10.
[0086] The associating means comprise supports 11, each of them
comprising in turn a first sidebar 14 and a second sidebar 15
parallel therebetween; for instance, the sidebars 14, 15 are
cylindrical stems. The sidebars 14, 15 are pivotably mounted on a
small elongated plate 16 orthogonal to the sidebars 14, 15. In the
example, two elongated plates 16 parallel therebetween are provided
for each support 11.
[0087] Moreover, the first sidebar 14, i.e. the sidebar closer to
the stock 2, and the elongated plates 16 are pivotably mounted on a
first flat protrusion 17 laterally extending from the stock 2, to
which the first protrusion 17 is firmly joined or integral.
[0088] The first and second sidebars 14, 15 are kept in a spaced
relation by the elongated plates 16, in order to define a housing
for a respective end 101, 102 of a bending member 10.
[0089] In fact they touch opposite sides of the bending member 10,
and in particular of said ends 101, 102, which are held between the
respective sidebars 14, 15. The first sidebar 14 is positioned at
the inner side of the bending member 10 with respect to the stock 2
and the second sidebar 15 is at the outside of the bending member
10.
[0090] Moreover, said ends 101, 102 are slightly jutting out in the
development direction 202 with respect to the sidebars 14, 15.
[0091] The first sidebar 14 also acts as a spacer, in order to keep
the bending member 10 slightly displaced from the stock 2.
[0092] Since the elongated plates 16 are rotatable about an axis 18
with respect to the first protrusion 17, the whole support 11 can
rotate about the same axis 18 following a flexing movement of the
bending member 10. That is, the support 11 rotates following the
movement of the respective end 101, 102 of the bending member 10
when the latter, flexing, varies its angle with respect to the
stock 2; in other words, a partial rotation of said end 101, 102 is
permitted.
[0093] Therefore, the bending member 10 can assume a simply curved
or arched shape, without being hampered by the supports 11 in said
flexing movement, thereby preventing the creation of longitudinal
stresses in the bending member 10.
[0094] Moreover, the sidebars 14, 15 have a curved profile (in the
example, a cylindrical profile) and are rotatable about the
respective longitudinal axes. Therefore, a translation movement of
the bending member 10 along its preferential development direction
202 is at least partially allowed, when required. In this case the
sidebars 14, 15 rotate during said translational movement, thus
reducing the mutual friction between the bending member 10 and the
sidebars 14, 15. A thin plate 19, for instance a metal plate, can
be locally interposed between the bending member 10 and each
respective sidebar 14, 15 in order to further reduce friction and
avoid wear of the bending member 10.
[0095] In other words, the associating means, in particular the
supports 11, are apt to prevent a side translation of a respective
tract of a bending member 10, i.e. a translation along a direction
203 perpendicular to its preferential development direction 202,
whereas it allows said tract an angular displacement or a flexing
movement, and a longitudinal translation along development
direction 202. To be more specific, said associating means are
arranged at the proximal end 101 and at the distal end 102 of the
bending member 10.
[0096] As a consequence, the described embodiment, as well as
permitting the connection of the bending members 10 to the stock 2,
allows the bending members 10 to easily flex towards the stock 2
during a loading phase of the device 1, and to counter-flex towards
the outside in a stroke towards the maximum discharge position.
[0097] However, in alternative embodiments the bending members 10
might be associated to the stock 2 in different manners.
[0098] For instance, the bending members 10 can be secured using a
flexible element surrounding one bending member 10 and the one on
the opposite side.
[0099] For instance, in an alternative embodiment, the bending
members 10 are associated to the stock 2 by means of supports
comprising only a first sidebar 14 and lacking said second sidebar
15. Each end 101, 102 of the bending members 10 is held against a
respective first sidebar 14 through a wire or flexible holding
means (for instance, a hook-and-loop fastener), which envelops the
end 101, 102 itself and the first sidebar 14, or attaches the end
101, 102 itself to said sidebar 14, or envelops the end 101, 102
itself and the corresponding end 101, 102 of the bending member 10
on the opposite side of the stock 2.
[0100] As a further alternative, at least one tract of a bending
member 10 is constrained with a rigid joint to the stock 2, that
is, said tract is tightly joined to the stock 2 so as to
substantially prevent any movement (translation, rotation and/or
flexion movement) of the tract itself with respect to the stock 2.
In other words, in said further alternative the associating means
are apt to join a tract of a bending member 10 to the stock 2 in
such a way as to prevent said tract from translating, with respect
to the stock 2, along said preferential development direction 202
and along a direction 203 orthogonal to said preferential
development direction 202, and from performing an angular
displacement with respect to the stock 2.
[0101] A combination of these methods, or of other methods, might
also be possible; moreover, different bending members 10 might be
associated through different methods.
[0102] The crossbow 1 comprises also at least two retaining members
or lever 21, arranged on opposite sides of the stock 2, symmetrical
with respect to said stock 2. Each retaining member 21 is pivoted
at a respective axis of rotation 22 and is associated to a portion
of at least one bending member 10 through a connection element 27.
The retaining member 21 retains the connection element 27 and
guides it during all phases of operation of crossbow 1, and
moreover determines the position and the displacement of fulcra of
respective tensioning means during said phases.
[0103] In the example, four retaining members 21 are provided, i.e.
two retaining members 21 on each side of the stock 2. Each
retaining member 21 is associated to a respective portion of the
connection element 27, said portion being situated at the same
height as one respective bending member 10.
[0104] Each pair of retaining members 21 is pivotably mounted, at
first ends 211, on a pin 24 top-and-bottom extending from a second
flat protrusion 23 laterally extending from the stock 2. Said axis
of rotation 22 corresponds to a longitudinal axis of said pin 24,
which is housed in seats or through holes 215 in said first ends
211 of the retaining members 21.
[0105] To be more specific, the second protrusion 23 is
sufficiently long to laterally stick out of the bending members 10
on the same side and it is sandwiched between the first ends 211 of
the respective pair of retaining members 21.
[0106] A second end 212 of each retaining member 21 is associated
to a portion of connection element 27, in particular to a
connection member 28, and to the respective bending member 10. Said
second end 212 comprises a "C"-shaped housing 213 opened towards
the bending member 10. A connection element 27, for connecting a
retaining member 21 to a bending member 10, comprises two
substantially semi-cylindrical connection members 28 and a
cylindrical collar 29 interposed between the semi-cylindrical
connection members 28 in aligned arrangement, i.e. two
semi-cylindrical connection members 28 are positioned symmetrically
with respect to a plane and are connected to each other by said
cylindrical collar 29.
[0107] The curved surface of the semi-cylindrical member 28 has
radial grooves 281, by means of which the semi-cylindrical
connection member 28 is interlocked with a respective second end
212 of a retaining member 21. When the semi-cylindrical member 28
and the retaining member 21 are clamped together, the
semi-cylindrical member 28 can rotate inside the "C"-shaped housing
213, due to the shape of the groove 281 and the corresponding
profile of the housing 213, so as to allow the retaining member 21
to vary its angle with respect to the bending member 10 and to
connection element 27.
[0108] A flat surface of the semi-cylindrical connection member 28,
which faces the bending member 10, has a dovetail joint 282 for
joining to a corresponding element 108 attached to a tract of the
bending member 10, preferably at a region positioned about half way
along its length. Thus, each semi-cylindrical connection member 28
is apt to move a portion of a respective bending member 10.
[0109] Therefore, the retaining member 21 is anchored to the
respective bending member 10 by means of said connection member 28.
Consequently, a flexing action on a bending member 10 determines an
angular displacement of the corresponding retaining member 21
around its axis of rotation 22. On the other hand, the retaining
member 21 keeps the respective bending member 10 in position inside
the supports 11 and prevents an overall translation of the whole
bending member 10 along its development direction 202.
[0110] Since it comprises two semi-cylindrical connection members
28, the connection element 27 is apt to be associated with two
bending members 10.
[0111] The crossbow 1 further comprises tensioning means of the
bending members 10, that is, means apt to bring the bending members
10 to a flexed position during a loading phase, and pushing means
30 of said projectile, apt to cooperate with the bending members 10
to transfer energy to the projectile to be launched.
[0112] The pushing means include a flexible pushing member 31, such
as, for example, a propulsive wire for pushing a projectile, and at
least two lever arms or pushing arms 32 positioned on opposite
sides of the stock 2 and connected to each other by the flexible
pushing member 31.
[0113] In the example, two pushing arms 32 are provided, which
laterally extend from the stock 2 and pass in between the bending
members 10 on the same side. Each pushing arm 32 is pivoted at a
respective first axis of rotation 33.
[0114] In the embodiment illustrated, the overall structure is such
that each side of the stock 2 has two bending members 10 opposite
to each other with respect to a plane on which the pushing arms 32,
and in particular cam sections 323, lie and on which their rotation
movement takes place, in order to create, overall, a group of four
bending members 10 symmetrical with respect to the longitudinal
development direction 201 of the stock 2.
[0115] To be more specific, the pushing arm 32 has a slot 35, in
which the cylindrical collar 29 of a respective connection element
27 is positioned idle. Therefore, the pushing arm 32 is pivoted at
the connection element 27 and its axis of rotation 33 substantially
corresponds to a longitudinal axis of said cylindrical collar 29.
To be more specific, the slot 35 is a hole.
[0116] Moreover, the pushing arms 32 are hinged each other, in
particular first ends 321 of the pushing arms 32 are pivoted on a
pivot body 82. The pivot body 82 is slidingly associated to the
stock 2 in order to run parallel to said longitudinal development
direction 201 along a guide track or rail 84, which for instance is
joined to the stock 2 and positioned parallel to the longitudinal
development direction 201.
[0117] During rotation of the pushing arms 32 around said first
axes of rotation 33, the pushing arms 32 rotate also around a
second determined axis 83, corresponding with an axis of the pivot
body 82; the second axis of rotation 83, which preferably is
orthogonal to the longitudinal development direction 201, moves
with the pivot body 82 along the guide rail 84.
[0118] A section 323 of the pushing arm 32, comprised between the
first end 321 and the slot 35, behaves like a cam, i.e. transforms
an angular displacement into a linear displacement. That is, since
the pivot body 82 is constrained to the guide rail 84 and cannot
move towards a side of the stock 2 perpendicularly to the
longitudinal direction 201, a rotation of the cam section 323 about
said first axis of rotation 33 entails also a translation of the
slot 35, and of the connection element 27 housed therein, along a
direction 203 substantially perpendicular to the longitudinal
direction 201, and vice versa. More specifically the axis of
rotation 33 moves along an arched path determined by the retaining
members 21.
[0119] Therefore, the cam sections, or cams, 323 are comprised in
the tensioning means of the bending members 10, i.e. they are apt
to deform the bending members 10 by means of a rotation movement.
To be more specific, the tensioning means comprise at least two
cams 323 positioned at opposite sides of the stock 2, symmetrical
with respect to said stock 2. Each cam 323 is pivoted at a
respective first axis of rotation 33 and is associated to at least
one corresponding bending member 10. In particular, the connection
elements 27 connect the cams 323 to the bending members 10.
[0120] In other words, thanks to the connection element 27 and the
pivoting methods, a portion of each bending member 10 is associated
idle to the respective slot 35 so as to allow said portion of
bending member 10 to make a translation movement together with the
slot 35; then the first axis of rotation 33 makes translation
movements together with a portion of the respective bending members
10. In particular, said translation movement substantially takes
place in the direction 203 orthogonal to the preferential
development direction 202 of the bending member 10 and is
constrained on an arched path determined by the rotation of the
retaining members 21 around axes 22.
[0121] That is, an angular displacement of the pushing arms 32, and
in particular a rotation movement of said cam sections 323 around
said first axes of rotation 33, creates a flexing action on the
corresponding one or more bending members 10, causing a flex
variation of the bending members 10 themselves, and a rotation
movement of the retaining members 21. Vice versa, a flex variation
of the bending members 10 creates a rotating action on the
corresponding pushing arms 32 and retaining members 21.
[0122] The rotation of the pushing arms 32 in a first rotation
direction determines, by means of the cams 323 and the connection
elements 27, a rotation of the retaining members 21 and a flexing
of the bending members 10 during a loading phase of the crossbow 1;
during a launch phase of said projectile, a return of the bending
members 10 towards said rest condition determines, by means of the
cams 323 and the connection elements 27, a rotation in the opposite
direction of the pushing arms 32.
[0123] In other words, the pushing arms 32, during a rotation
movement, are apt to cooperate with the tensioning means, i.e. the
cams 323, to realize a transfer of energy to said bending members
10 during the loading phase of the crossbow 1, and a transfer of
energy from said bending members 10 to said pushing means 30 during
the projectile launch phase.
[0124] To be more specific, in the present embodiment said first
rotation direction during the loading phase is directed towards
said proximal end 205 of the stock 2, and said rotation in the
opposite direction during the launch phase is directed towards said
distal end 206 of the stock 2.
[0125] In the present embodiment, each pushing arm 32 forms a
single part with a respective cam 323; in this case, the axes of
rotation 33 of the cam 323 and of the respective pushing arm 32 are
the same.
[0126] As illustrated in FIG. 2B, the pushing arms 32 can be
rotated between a first maximum loading position, with pushing arms
32 rotated towards the proximal end 205 of the stock 2 and
corresponding to a maximum flexing of the bending members 10, and,
as illustrated in FIG. 2C, a second maximum discharge position
following the launch of the projectile, with pushing arms 32
rotated towards the distal end 206 of the stock 2 and corresponding
to a maximum counter-flexing of the bending members 10. Between
said first and second positions, there is a neutral position, at
which the bending members 10 do not have accumulated elastic
energy, as they are in a rest condition in a non-deformed state, as
illustrated in FIG. 2A.
[0127] To be more specific, in the present embodiment the bending
members 10 flex towards the stock 2 during the loading phase and
counter-flex towards the outside in the launch phase: this is due
to the position of the second axis of rotation 83 with respect to
the plane on which the first axes of rotation 33 lie, in relation
to the rotation movement described by the cams 323. In other words,
in the neutral position the second axis of rotation 83 is between
the distal end 206 and said plane of the first axes of rotation
33.
[0128] It is evident, in any case, that an opposite flexing method
for the bending members 10 may also be used. In fact, a flexing
method away from or closing to the stock 2 during the loading phase
may be selected through an opportune dimensioning and assembly of
the cams 323 and pushing arms 32, and is substantially unrelated to
the other specific characteristics of the embodiments
described.
[0129] A second end 322 of the pushing arm 32 supports a pair of
pulleys 145, 146 rotatably associated to it. Therefore, two pairs
of pulley 145, 146 are provided, arranged on opposite sides of the
stock 2, each pair being associated to a respective pushing arm
32.
[0130] In the example, the pulleys 145, 146 are positioned at
opposite side of the second end 322, i.e. a first pulley 145 is at
top side of the pushing arm 32 and a second pulley 146 is at bottom
side of the pushing arm 32.
[0131] The first and second pulleys 145, 146 associated to a same
pushing arm 32 are rotatably connected for a coordinated rotation
around an axis of rotation 150. To be more specific, the first and
second pulleys 145, 146 rotate jointly, since they are associated
or fastened to a same common pivot 147 rotating jointly with them.
The pivot 147 extends orthogonal to the surface of the pulleys
themselves. The pivot 147 is housed idle in a slot, or in a through
hole, 36 provided in the second end 322 of the pushing arm 32 and
can rotate in this hole 36 with respect to the axis 150. The axis
150 makes translation movements together with the second end 322 of
the respective pushing arm 32.
[0132] Preferably, the pulleys 145, 146 lie on planes which are
parallel to each other, and in particular are parallel to the
longitudinal direction 201 and to the plane on which the pushing
arms 32 move.
[0133] In the present disclosure, the term "pulley" should be
generally understood as a rotatable member having a profile or a
side edge, or a part of profile, apt to wind at least partially a
flexible member during a rotation movement, or apt to house a
portion of a flexible member passing around it; in any case, it is
not required that the side edge or profile of a pulley define a
closed line; in fact, the figures show a pulley 145 which has an
interrupted side edge.
[0134] A side edge, or profile, of the first pulley 145 has a track
or groove 1451 in which one end 311 of the flexible pushing member
31 is supported and/or secured and in which the flexible pushing
member 31 itself winds. In other words, the first pulley 145 is
interposed between the pushing arm 32 and the flexible pushing
member 31.
[0135] The first pulley 145 has an eccentric side edge with respect
to the longitudinal axis 150 of the pivot 147; the first pulley 145
has a very pronounced eccentricity: in fact, it has a substantially
elliptical profile, wherein the pivot 147 is positioned close to
the side edge at the major axis of the ellipse.
[0136] The flexible pushing member 31 connects the pushing arms 32
to each other; to be more specific, it connects the first pulley
145a of one pushing arm 32a to the first pulley 145b of the other
pushing arm 32b, and, in said the rest condition, it is partially
wound on said first pulleys 145.
[0137] The crossbow 1 comprises a flexible force member 37, such as
for example a wire, which commands or forces the rotation movements
of the pushing arms 32.
[0138] Each of first lengths, in particular ends 371a, 371b, of the
flexible force member 37 is secured in a track or groove 1461 of a
side edge of a respective second pulley 146, in which the flexible
force member 37 itself winds. In other words, the second pulley 146
is interposed between the pushing arm 32 and the flexible force
member 37.
[0139] Also the second pulley 146 has an eccentric side edge with
respect to the longitudinal axis 150 of the pivot 147, even though
in the example the second pulley 146 is less eccentric than the
first pulley 145.
[0140] A second length or intermediate region 372 of the flexible
force member 37 goes round a tightener element, for instance a
frame 61, associated to the stock 2; to be more specific, said
intermediate region 372 is housed in a track or groove 611 of a
side edge of said frame 61.
[0141] Also the flexible force member 37 connects the pushing arms
32 to each other. To be more specific, it connects the second
pulley 146a of one pushing arm 32a to the second pulley 146b of the
other pushing arm 32b; moreover, in said rest condition, the
flexible force member 37 is partially wound on said second pulleys
146 and rounds said frame 61.
[0142] The flexible members 31, 37 are secured to the respective
pulleys 145, 146 in such a way that, during an angular displacement
of a pair of pulleys 145, 146 around the axis of rotation 150, the
unwinding of the flexible pushing member 31 from the first pulley
145 is accompanied by the winding of the flexible force member 37
on the second pulley 146, and vice versa.
[0143] The frame 61 is associated and secured to the stock 2 in a
lockable slide arrangement, for instance by means of a socket 62
fastened to the frame 61 and cooperating with a proper counterpart
element 63 attached to the stock 2. Moreover, the cooperation
between the socket 62 and the counterpart element 63, for instance
through a dove-tail joint, is such as to allow a sliding movement
of the frame 61 along the stock 2 and its longitudinal development
direction 201.
[0144] A locking lever 64 is pivoted to the stock 2, at a pivot 65
integral with a side of the stock 2 and housed in a first seat 641
of the lever 64. A connecting rod 66 is pivoted to the socket 62 at
a pin 621 and to the locking lever 64 at a second seat 642. The
second seat 642 is surrounded by a "L"-shaped slot 643 for an end
of the connecting rod 66.
[0145] When the locking lever 64 is rotated towards a locking
position shown in FIG. 10, the frame 61 is pressed towards the
proximal end 205 of the stock 2 and the flexible force member 37 is
tightened. When the second seat 642 is above a line connecting the
first seat 641 and the pin 621, the frame 61 is locked: in fact,
the force exerted by the flexible force member 37 on the frame 61
is transmitted to the locking lever 64 by the connecting rod 66 and
the resulting torque is in the opposite direction of an unlocking
rotation of the locking lever 64.
[0146] When the flexible force member 37 is to be loosened by a
user, the locking lever 64 is rotated in the unlocking direction
shown in FIG. 13. Consequently, the second seat 642 goes below the
line connecting the first seat 641 and the pin 621; after this
point, the frame 61 is moved towards the distal end 206 of the
stock 2 and the flexible force member 37 is loosened, as shown in
FIG. 12 for a non-operative position of the crossbow 1.
[0147] Contrast means 50, associated to the stock 2 and operatively
connected to the pushing arms 32, and in particular to cams 323,
may also in case be provided in order to dampen the motion of the
pushing arms 32. Depending on the extent of the counter-flexing
permitted for the bending members 10 (also related to their
rigidity) and the choices for the dimensioning of the components of
the crossbow 1, the contrast means 50 may also dampen the motion of
the bending members 10 by means of the interaction with the cam
sections 323 of the pushing arms 32.
[0148] Said contrast means 50, for example, include an end wall 51
from which a hollow cylinder 52 protrudes along the longitudinal
direction 201, a spring 53, a thrusting member 54 for said spring
53.
[0149] The spring 53 is positioned around the hollow cylinder 52
and against the end wall 51. The thrusting member 54 has a
thrusting wall 541 apt to thrust or compress the spring 53 against
the end wall 51. A rod 55 protrudes from the thrusting wall 541 and
is apt to slide inside a bore 521 of the hollow cylinder 52, as a
guide for a translation movement of the thrusting member 54 along
said longitudinal direction 201.
[0150] The thrusting member 54 is associated to a slide 25, to
which the pivot body 82 is connected. The slide 25, which is
associated to the stock 2 and positioned between the cams 323, is
apt to move parallel to the longitudinal development direction 201
along the guide rail 84. In the example, the slide 25 has a
dove-tail housing 251 apt to slidingly receive the guide rail
84.
[0151] The contrast means 50 are arranged so as to apply a force
against the cam sections 323 when the pushing arms 32 are beyond
said neutral position towards said second maximum discharge
position. In fact, when the pushing arms 32 have passed the neutral
position, the thrusting wall 541 is in touch with the spring 53 and
pushes against it. This way, the thrusting member 54 compresses the
spring 53 and a slowing down of the motion of the pushing arms 32
is obtained thanks to the transfer of energy to the spring 53.
[0152] When the pushing arms 32 are between said first maximum
loading position and said neutral position, the thrusting wall 541
is not in contact with the spring 53 and, therefore, the contrast
means 50 do not have any influence on the motion of the pushing
arms 32 themselves.
[0153] These same elastic means represented by the spring 53
cooperating with the thrusting member 54 can bring the pushing arms
32 back towards the neutral position, so that at the end of the
launch phase they are in the neutral position again.
[0154] In an alternative embodiment, contrast means are not present
and the entire effort of braking the parts in movement and
recovering the neutral position is charged on the bending members
in their counter-flexing motion and subsequent regaining of their
neutral position.
[0155] Before a projectile is launched, the crossbow 1 is initially
in the neutral condition (FIG. 2A), wherein the bending members 10
are in a rest condition and the flexible pushing member 31 is
partially wound on the first pulleys 145 and extending between
them.
[0156] During a loading phase of the crossbow 1, the user pulls the
flexible pushing member 31 towards the proximal end 205 of the
stock 2, until the flexible pushing member 31 is engaged in the
fastening system 6. During this operation, the flexible pushing
member 31 is progressively unwound from the first pulley 145 on
each side and, due to the corresponding rotation of the first
pulleys 145 and second pulleys 146 around the axes 150, the
flexible force member 37 is progressively wound on the second
pulley 146 on each side.
[0157] As a consequence, the flexible force member 37 forces both
pushing arms 32 to rotate, in an initial direction, towards the
proximal end 205 of the stock 2 around the respective first axes of
rotation 33, and also around the second axis of rotation 83. That
is, the flexible force member 37 commands the rotation of the
pushing arms 32.
[0158] The rotation of the pulleys 145, 146 around the respective
axis of rotation 150, that is, around the translating axis 150 of
the pivot 147, is, therefore, coordinated with a respective pushing
arm 32 (and a respective cam section 323) for a synchronized
rotation of the pushing arm 32 itself (and of the cam section 323)
around the respective first axis of rotation 33. In other words,
the pulleys 145, 146 move synchronized with the respective pushing
arm 32, with a combined translation and rotation movement.
[0159] Since the connection elements 27 are constrained by the
retaining members 21, said rotation of the pushing arms 32 entails
that the pivot body 82 and the second axis of rotation 83 translate
towards the distal end 206 and the connection elements 27 translate
towards the stock 2, almost perpendicularly to the longitudinal
direction 201, accompanied by the rotation of the retaining members
21 around the respective axes 22.
[0160] As a consequence, the bending members 10 flex towards the
stock 2 and accumulate elastic energy proportional to their
flexing. A rotation of the ends 101, 102 of the bending members 10
with respect to the stock 2 is allowed by the supports 11 rotatable
around axes 18, and a limited translation of the ends 101, 102 of
the bending members 10 with respect to the supports 11 is allowed
by the rotatably mounted sidebars 14, 15.
[0161] When the maximum loading position, corresponding to a
maximum flexing of the bending members 10, is reached, the bending
members 10 are in the bent configuration illustrated in FIG. 2B;
moreover, the flexible pushing member 31 is at its maximum
unwinding from the first pulleys 145 and the flexible force member
37 is at its maximum winding on the first pulleys 146. A projectile
(not shown) can be placed in a suitable track 8 on the stock 2 and
the crossbow 1 is ready for launching.
[0162] Pulling of the trigger 7 releases the flexible pushing
member 31, and starts a projectile launch phase. The bending
members 10 tend to return to the rest position, that is, the
non-deformed neutral position, and therefore push the cam sections
323 towards the outside, almost perpendicularly to the longitudinal
direction 201. The movement of the bending members 10 is
constrained and accompanied by the rotation of the retaining
members 21 around the respective axes 22.
[0163] Since the cam sections 323 are pivoted on the pivot body 82,
the result of the pushing action of the bending members 10 on the
cam sections 323 is that the cam sections 323 rotate in the
opposite direction with respect to the loading phase. That is, the
pushing arms 32 rotate too, towards the distal end 206 of the stock
2, and the pivot body 82 moves toward the proximal end 205.
[0164] During this movement, the flexible force member 37 exerts a
torque on the second pulleys 146, which is transmitted to the first
pulleys 145. Said pulleys 145, 146 rotate in an opposite direction
with respect to the loading phase. The flexible force member 37 is
progressively unwound from the second pulleys 146 and the flexible
pushing member 31 is progressively wound on the first pulleys 145.
In other words, the combination of the translation motion of the
ends 322 of the pushing arms 32 with the rotation motion of the
first pulleys 145 draws the flexible pushing member 31 and also
winds it in the grooves 1451 of the first pulleys 145. Therefore,
the pushing arms 32 pull the flexible pushing member 31 along the
projectile track 8 and energy is transferred to the projectile by
the push of the flexible pushing member 31 against it.
[0165] When the neutral position is reached, due to the inertia of
the moving parts, i.e. the pushing arms 32, the retaining members
21, the pulleys 145, 146, and the bending members 10, said moving
parts pass the neutral position and continue their run beyond the
neutral position, tending towards the maximum discharge position,
shown in FIG. 2C.
[0166] In this portion of the stroke, between the neutral position
and the maximum discharge position, the bending members 10 are in a
flexed position towards the outside of the stock 2 (that is, in a
counter-flexed configuration with respect to the loaded position).
Moreover, the flexible pushing member 31 is further wound on the
first pulleys 145 with respect to the neutral position; the
flexible force member 37 is further unwound from the second pulleys
146.
[0167] In case of an especially high residual kinetic energy (for
example, in case of a very light projectile or of dry firing), the
pushing arms 32 may reach said maximum discharge position, in which
they are rotated towards the distal end 206 of a maximum angle with
respect to the neutral position. In this position, the bending
members 10 have a maximum flexing towards the outside of the stock
2. Moreover, there is the maximum winding of the flexible pushing
member 31 on the first pulleys 145, which are almost in contact
with each other, and the maximum unwinding of the flexible force
member 37 from the second pulleys 146. As the axes 150 move forward
and towards the stock 2, the second pulleys 146 give length of
flexible force member 37 to second the movement of the pushing arms
32 and the first pulleys 145 take any length of propulsive flexible
pushing member 31 that is made available, so that the rotation of
the pulleys 145, 146 is not impeded and at the same time no
flexible members 31, 37 goes slack. This is in particular obtained
through a proper design of the side edges and profiles of the
pulleys 145, 146.
[0168] Additionally, in this portion of the stroke the movement of
the pushing arms 32 is opposed by the contrast means 50 (if they
are present), which slow down the pushing arms 32 and also
dissipate part of the kinetic energy; according to the methods
described, these contrast means 50 only operate starting from the
neutral position towards the maximum discharge position.
[0169] Thanks to the combined action of the bending members 10 and
the spring 53, which tend to return to the respective non-deformed
conditions, the entire system is then brought back to the neutral
position, where it stops.
[0170] From the above description it is understood how the
end-of-stroke shock is substantially eliminated, because the stop
of the components at the end of the useful run is not sudden as
with the known art, but takes place within the stroke between the
neutral position and the discharge position, and return. This
enables a greater reduction in the structural stresses, in the
noise and in the risks related to the use of too light a projectile
or no projectile at all. It also implies an overall smoother
operation and it removes any apprehension or discomfort,
psychological or physical, which may accompany the use of known-art
devices, especially the more powerful ones in combination with
lighter arrows.
[0171] The synchronization of the motion of the pushing arms 32 one
with the other guarantees a balanced pull on the flexible pushing
member 31 and this absolves a necessary condition for accuracy.
[0172] The use of solid levers as the primary mover, i.e. of cams
323 as tensioning means, acting on the bending members 10 allows
for higher forces and therefore permits the use of more rigid
bending members 10 compared to known-art devices. This allows the
device to handle more energy and it also makes it possible to
considerably increase (with respect to the known art) the ratio
between the draw length and the extent of the shifting of the
masses of the bending members 10, thereby increasing the efficiency
of the conversion between potential and kinetic energy.
[0173] An adequate profiling of the cam sections 323 and of the
pulleys 145, 146 also makes it possible to obtain a more extensive
force-draw curve reshaping than in known-art devices. In particular
it enables a more marked reduction in the maximum loading effort.
The use of first pulleys 145 rotating with respect to the pushing
arms 32 allows for greater design freedom in order to obtain the
desired force-draw curve. In fact, the shape of this curve may be
adapted to the desired requirements by envisaging an opportune
profile and rotation angle for the pulleys. The more deformed the
bending members 10 are, the more force is required for a further
deformation of them, i.e. the higher is the required torque acting
on the cam sections 323 and on the pushing arms 32 due to the force
exerted by the flexible force member 37. In other words, the torque
acting on the second pulleys 146 should increase during the loading
phase. This is achievable by providing an eccentric side edge for
the first pulleys 145: in this case the lever arm, with respect to
axis 150, for the force exerted by the flexible pushing member 31
increases during the loading phase, and then an increasing torque
on the second pulleys 146 is obtainable through an approximately
constant force exerted by the user on the flexible pushing member
31.
[0174] Advantageously, as shown in FIG. 7, the distance D1 between
a plane on which the first pulleys 145 lie and a plane on which the
first ends 321 of the pushing arms 32, pivoted on the pivot body
82, lie is greater than the distance D2 between a plane on which
the second pulleys 146 lie and said lying plane of the first ends
321.
[0175] Since the force transmitted by the flexible force member 37
to each pushing arm 32 is greater than the force transmitted by the
flexible pushing member 31 to the same pushing arm 32, the
difference between said distances D1 and D2 allows to compensate
for the difference between said forces; that is, it allows to
reduce or cancel out the torque acting on the pushing arm 32 on a
plane perpendicular to the rotation plane of the pushing arm 32
itself.
[0176] It is also possible to modify the characteristics of the
crossbow 1, adapting them to the use requirements, by replacing the
bending members 10 with other bending members of different elastic
characteristics, so as to have a different level of stored
energy.
[0177] Note that the possibility of easily taking apart the
crossbow 1 and replacing its components is linked to the fact that,
in the neutral position, there are no members or components in
elastic tension; therefore, the taking apart and the assembly do
not require either special tools (e.g. presses) or special caution
on the part of the user. In fact, the crossbow 1 can be easily and
safely disassembled.
[0178] Further, in the launch phase the rotation movement of the
first pulleys 145 towards the longitudinal axis 201 of the stock 2
makes it possible to substantially cancel out the inertia of the
pulleys 145 with respect to the stock 2 and, therefore, the
structure of the crossbow 1 and the user are subject to lower
stresses.
[0179] Several variants of the described embodiment are
possible.
[0180] There may also be auxiliary pushing means (not shown) in
order to further increase the maximum power of the crossbow 1,
these auxiliary pushing means including at least one member with
elastic behavior (spring or hydraulic and/or pneumatic device or
other) apt to accumulate elastic energy during the loading phase of
the crossbow 1 and return it to said pushing means 30 during the
projectile launch phase. Said auxiliary pushing means may be
connected to the slide 25 and, in particular, be housed at the
front of the stock 2, that is, in a position which is substantially
opposite to said contrast means 50; in fact, the action of these
auxiliary pushing means would be similar to the action exerted by
the spring 53, but directed in the opposite direction and active in
the phase in which these contrast means 50 are not operative.
[0181] These auxiliary pushing means may also be side by side to
said contrast means 50, for example, by making that the spring 53
is joined in a stable manner to the end wall 51 and to the
thrusting wall 54, so that it may accumulate elastic energy when
the pushing arms 32 are brought from the neutral position to the
maximum loading position and return it in the opposite
direction.
[0182] As already said, in the described embodiment each pushing
arm 32 forms a single part with a respective cam section 323. In
alternative embodiments, the cam, i.e. the tensioning means apt to
flex the bending member, is distinct from the pushing arm, i.e. the
arm supporting the flexible pushing member 31 and the pulleys 145,
146; in other words, the cam and the pushing arm may be two
distinct parts. In this case the axis of rotation of the cam and
the axis of rotation of the pushing arm would be distinct. For
example, the cam may be pivoted to the bending members 10 through a
connection element 27 and the pushing arm may be directly pivoted
to the stock 2. The transmission of the rotation movement from a
cam to a respective arm (and vice versa) is realized for instance
through a connecting rod which is pivoted to said cam and to said
pushing arm.
[0183] The single flexible pushing member 37 may be replaced by two
flexible pushing members, arranged on opposite side of the stock 2,
each one having a first end associated to a respective second
pulley 146 and a second end associated to the frame 61.
[0184] A second embodiment of a device for launching a projectile,
in particular a crossbow, is shown in FIGS. 14A to 16, where it is
indicated with the reference number 401. Elements having the same
function and structure maintain the same reference number as in the
embodiment previously described and, therefore, they are not
described again in detail.
[0185] FIGS. 14A, 14B and 14C illustrate, respectively, the
crossbow 401 in a neutral (rest) condition, in a loaded condition,
and in a maximum discharge condition.
[0186] The crossbow 401 comprises retaining members or levers 420
to hold and constrain the bending members 10, through the
connection elements 27, in a proper position with respect to the
stock 2 during all operative phases of the crossbow 401, and,
moreover, to determine the position and the displacement of fulcra
of tensioning means during said phases.
[0187] In the example, four retaining members 420 are provided,
i.e. two retaining members 420 on each side of the stock 2, and
each one is associated to a respective bending member 10.
[0188] Each retaining member 420 comprises a first arm or lever
421, which is similar to the retaining lever 21 of the embodiment
previously described and it is not described in detail again.
[0189] The first lever 421 is attached to a second lever 422 or
side appendix, which laterally extends from the first lever 421
towards the outside of the stock 2; the first lever 421 and the
second lever 422 of the same retaining member 420 rotate jointly
around an axis 22, for instance being integral one and the
other.
[0190] In the example, the first lever 421 and the second lever 422
slant each other and form an angle greater than 90 degrees.
[0191] Each pair of retaining members 420 on the same side of the
stock 2 is pivotably mounted on a respective second flat protrusion
23 laterally extending from the stock 2, to which the second
protrusion 23 is firmly joined or integral.
[0192] The flat protrusion 23 lies between the respective retaining
members 420, which are pivoted to said second protrusion 23 by
means of a pin 24 top-and-bottom extending from the second
protrusion 23; in particular, the pin 24 is positioned in a seat or
through hole 423 of the retaining member 420. To be more specific,
said hole 423 is at the vertex of the angle formed by said first
lever 421 and second lever 422, i.e. at first ends of them.
[0193] An axis of rotation 22 of the retaining member 420
corresponds to a longitudinal axis of said pin 24.
[0194] A second end 412 of each first retaining lever 421 is
associated to the respective bending member 10, by means of a
"C"-shaped housing 413 substantially similar to the "C"-shaped
housing 213 previously described. A second end 425 of each second
retaining lever 422 is associated to a flexible force member 437,
for instance through a perforated cylinder 428 pivoted to both
second retaining levers 422 on the same side of the stock 2.
[0195] The crossbow 401 has two flexible force member 437, one on
each side of the stock 2, each of them having a first end 438
associated to a second pulley 146 and a second end 439 associated
to a retaining member 420. The second end 439 of the flexible force
member 437 is associated to the retaining member 420, in particular
to its second lever 422, by means of said perforated cylinder 428
and a stopper 440 fastened to the flexible force member 437.
[0196] The loading phase and the launch phase for crossbow 401 are
similar to the corresponding phases for crossbow 1 previously
described; therefore they are not described in further detail.
[0197] The main difference is that, due to a slight rotation of the
retaining members 420 during the loading/launch phase, the second
retaining lever 422 goes towards/away from the respective pushing
arm 32 and therefore a longer length or stretch of flexible force
member 437 is to be wound/unwound on the second pulley 146, with
respect to crossbow 1. Also the tension on the flexible force
member 437 will be lower, so allowing for reduced cross section of
the flexible force member 437 itself. Therefore the second pulley
146 can feature a smaller minimum radius and a larger maximum one;
consequently, its eccentricity can be chosen in a larger interval
making it easier to find the desired solution for getting the
required force-draw curve.
[0198] Moreover the retaining members 420, and in particular the
second retaining levers 422, cooperate with the bending members 10,
in order to transmit a portion of energy to the flexible pushing
member 31. In fact in the launch phase the rotation of the second
retaining levers 422 towards the proximal end 205, moving away from
the pushing arms 32 rotating towards the distal end 206, entails a
further torque on the second pulleys 146, and then on the first
pulleys 145, transmitted through the flexible force members 437. So
the overall pushing action on the projectile is more balanced and a
better structural efficiency is achieved. For instance, the pushing
arms 32 can be lighter, because they are subjected to a lower
stress.
[0199] A third embodiment of a device for launching a projectile,
in particular a crossbow, is shown in FIGS. 17 and 18, where it is
indicated with the reference number 501; it comprises further
technical characteristics which may, however, be present alone or
in combination or may be applied to the embodiments previously
described. Elements having the same function and structure maintain
the same reference number as in the embodiments previously
described and, therefore, they are not described again in
detail.
[0200] The crossbow 501 comprises two pushing arms 32, and the
second end 322 of each pushing arm 32 supports a pair of pulleys
145, 146 rotatably associated to it. In the example, the pulleys
145, 146 are positioned at opposite side of the second end 322,
i.e. a first pulley 145 is at top side of the pushing arm 32 and a
second pulley 146 is at bottom side of the pushing arm 32.
[0201] In the example, the first pulley 145 is cylindrical, i.e.
its side edge is circular and not eccentric with respect to a
longitudinal axis 550 of a pivot 547 to which it is perpendicularly
associated; the first pulley 145 and the pivot 547 rotate
jointly.
[0202] Moreover, the side edge of the first pulley 145 has a
helix-like track or groove 1452 which allows the winding of a
plurality of turns of flexible pushing member 31.
[0203] The pivot 547 is housed in a first slot, or in a first hole
536 provided in the second end 322 of the pushing arm 32, and can
rotate idle in this first hole 536 around the axis 550. The axis
550 makes translation movements together with the second end 322 of
the respective pushing arm 32.
[0204] In the example, the second pulley 146 is eccentric and
approximately semi-elliptical, i.e. its side edge and its groove
1461 have a semi-elliptical shape and a pivot 548 is
perpendicularly fastened near the side edge at the major axis of
the ellipse. A wheel 549 is perpendicularly fastened to the
opposite side of the pivot 548. The wheel 549, the second pulley
146, and the pivot 548 rotate jointly.
[0205] The pivot 548 is housed in a second slot, or in a second
through hole 537 provided in the second end 322 of the pushing arm
32, near the first hole 536; the pivot 548 can rotate idle in this
second hole 537 around its longitudinal axis 551. The axis 551
makes translation movements together with the second end 322 of the
respective pushing arm 32.
[0206] To be more specific, the second pulley 146 is at the bottom
side of the pushing arm 32, whereas the wheel 549 is at the top
side of the pushing arm 32, i.e. at the same side of the first
pulley 145. Moreover, the wheel 549 is operatively connected to,
and cooperates with, the pivot 547 of the first pulley 145, for
instance being in contact with it, for a coordinated rotation of
the first pulley 145 with the second pulley 146. For instance, the
wheel 549 is a toothed wheel and the pivot 547 has a corresponding
grooved or toothed portion, and the wheel 549 mates the pivot 547
through said toothings. Alternatively, the wheel 549 and the pivot
547 are frictionally coupled, i.e. they are mated through friction
between the surface of the pivot 547 and the circumferential
surface of the wheel 549.
[0207] The loading phase and the launch phase for crossbow 501 are
similar to the corresponding phases for crossbow 401; therefore
they are not described in further detail.
[0208] The main difference is that, due to the first pulley 145 and
second pulley 146 rotating about different axes and coupled each
other through the wheel 549 and the pivot 547, the first pulley 145
and the second pulley 146 on the same side rotate in opposite
directions and have different revolution numbers.
[0209] In this embodiment the desired force-draw curve can be
obtained by a proper design of the second pulley 146 and its
eccentricity, while the first pulley 145 can be simply
cylindrical.
[0210] Moreover, by modifying the diameter of the wheel 549 (or of
the pivot 547 of the first pulley 145) it is also possible to vary
the number of revolutions carried out by the first pulley 145 and
the number of windings or turns of the flexible pushing member 31
on it, for a same shift of the pushing arm 32 along the flexible
force member 437; in this way it is possible to vary the draw
length while leaving the total width substantially unchanged. This
is particularly advantageous for obtaining laterally compact
devices with high power and reduced accelerations on the
projectile.
[0211] As shown in FIG. 17 and in detail in FIG. 18, in the present
embodiment the flexible force member 437 is not wound on the
respective second pulley 146 when the crossbow 501 is in the
neutral or rest condition; in fact the flexible force member 437 is
fastened at the groove 1461 of the second pulley 146 so as to be
simply tangential to its side edge in said condition. During the
loading phase, the flexible force member 437 gets progressively
wound on the second pulleys 146, whereas during the launch phase it
gets progressively unwound from the second pulleys 146, as already
described for the other embodiments.
[0212] During the stroke between the rest condition and the maximum
discharge position, the rotation of the second pulley 146 gives
additional distance between its rotation axis 551 and the
corresponding second end 425 of the retaining side appendix 422 to
which the other end 439 of the flexible force members 437 is
fastened, due to the eccentricity of the second pulley 146 itself,
so that a rotation movement of the pushing arms 32 towards the
distal end 206 is allowed even if no flexible force member 437 is
wound on the second pulleys 146. It is evident that this feature
can be analogously applied also to other embodiments.
[0213] In another embodiment the first pulley 145 can be
non-cylindrical and/or its groove 1452, apt to wind the flexible
pushing member 31, can describe an irregular helix. This would
allow greater design freedom in obtaining the desired operation in
relation to the winding/unwinding action and in compensating
altitude differences of said flexible pushing member 31 relative to
the stock 2 during all operative phases. To the same end the plane
on which the cam sections 323 of the arms 32 lie may be tilted
along with at least some of the other components, for instance said
plane may be tilted with respect to the projectile track 8 or to a
proximal portion of the longitudinal development direction 201 of
the stock 2.
[0214] A detail of a fourth embodiment of a device for launching a
projectile is shown in FIG. 19, where it is represented in a first
operative position. Said fourth embodiment, which is indicated with
the reference number 601, comprises further technical
characteristics which may, however, be present alone or in
combination, or may be applied to the embodiments previously
described. Elements having the same function and structure maintain
the same reference number as in the embodiments previously
described and, therefore, they are not described again in
detail.
[0215] The crossbow 601 comprises retaining members 620 which are
similar to the retaining members 420 of the crossbow 401 previously
described. To be more specific, each retaining member 620 is
pivoted to the stock 2 at a rotation axis 22 and comprises a first
arm or lever 421 associated to a respective bending member 10 by
means of a "C"-shaped housing 413, and a second lever 422 or side
appendix, which laterally extends from the first lever 421 towards
the outside of the stock 2. In the example, the first lever 421 and
the second lever 422 slant each other and form an angle greater
than 90 degrees. The first lever 421 and the second lever 422 of
the same retaining member 620 rotate jointly around said axis 22,
for instance being integral one and the other.
[0216] On each side of the stock 2, a return pulley 628 is
rotatably associated to a retaining member 620; in particular, the
return pulley 628 is interposed between second ends 425 of the
second levers 422 on the same side, and is pivoted to them at a
rotation axis 650.
[0217] A flexible force member 637 has a first end 638a fastened or
associated at the track 1461 of the second pulley 146, a second end
638b fastened or associated at the pushing arm 32, in particular at
a side protrusion 326 thereof, and a intermediate region 639 going
around the return pulley 628, for approximately half a turn.
[0218] Said intermediate region 639, which is interposed between
said first and second ends 638a, 638b, is housed in a track or
groove 6281 of the return pulley 628. Therefore, said return pulley
628 is a tightener element of the flexible force member 637, i.e.
it tights the flexible force member 637 and keeps the latter in
tension; moreover it allows a sliding of the flexible force member
637 with respect to the retaining members 620.
[0219] Therefore, when the pushing arm 32 and the respective
retaining member 620 rotate during all phases of operation of the
crossbow 601, going towards/away each other, the winding/unwinding
of the flexible force member 637 on/from the second pulley 146 is
accompanied by a corresponding rotation of the return pulley 628
about its rotation axis 650.
[0220] With respect to previous embodiments, this arrangement
approximately doubles the length of flexible force member 637 to be
wound on the second pulley 146 and halves the tension on it, so
allowing a reduction of its diameter and further increasing the
scope for force-draw curve reshaping and providing a solution
better suited for higher energies. In an alternative embodiment,
each return pulley 628 is pivoted to the stock 2 instead of to a
retaining member 620. For instance, the return pulleys 628 are
pivoted to a frame similar to the frame 61 of the crossbow 1
previously described.
[0221] The principles at the basis of the present disclosure may be
applied not just to a crossbow, but also to a bow, to a catapult,
or to an apparatus for launching model aircraft or unmanned aerial
vehicles or for devices for experimental purposes.
[0222] The subject of the present disclosure has been described so
far with reference to its preferred embodiments. It is understood
that there may be other embodiments which relate to the same
inventive core, all included within the scope of the protection of
the claims laid out below.
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