Bow-Type Throwing Tool

Abstract

A bow-type throwing tool includes a central body, a nocking string for an arrow, and elastic energy storage mechanism operated by the traction of the string. The elastic energy storage mechanism includes: two opposed primary levers connected with hinging to the central body, the nocking string being constrained by its opposite ends to opposite free ends of the primary levers; two opposed axial action thrust accumulators, defined on the central body; a loading element of the axial action thrust accumulators configured to induce a compression in the thrust accumulators following a traction of the nocking string.

Description

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The invention relates to a bow-type throwing tool.

2. The Relevant Technology

Generally a bow comprises:

• • two limbs, which represent the elastically deformable parts;
  • two tips, to which one end of a loading string is constrained;

a loading string, through which the arrow is loaded and the bow is flexed;

• • a central riser, typically rigid, which joins the limbs.

Typically, there is a handle and an arrow rest on the central riser.

Today a type of bow that is known in jargon as the ‘compound bow’, is known and widespread, which has an eccentric pulley system that allows storing a greater amount of muscle energy in the limb system and reducing by a percentage, which normally ranges from 40% to 90%, the effort when the bow is stretched.

In jargon, the term let-off refers to that effect, generated by the mechanism, which allows pulling the thread or string of a compound bow or similar, reaching the full draw of the bow with a visibly reduced muscular effort compared to the traditional bow, in addition to allowing the shooter to remain with reduced effort in an aiming position with full drawn bow.

The let-off is measured with a percentage which represents the value of reduction in the effort necessary to maintain the bow completely drawn; for example, to maintain a bow loaded at 60 pounds drawn with a 70% let-off, we must exert an effort equal to only the remaining 30% of 70 pounds, i.e., 18 pounds.

The let-off, obtainable with the first compound bows with percentages from 35% to 50%, has significantly increased over the years and it is currently normal to find bows with let-off percentages of 80%.

In general, a bow is a mechanical system, as established by the standard, which transfers the energy stored during the loading step, known as the “draw”, to the arrow which transforms said energy into kinetic energy. The amount of energy that the arrow receives depends on the configuration of the bow, as can be clearly seen from the graphs in FIG. 42 and FIG. 43.

The energy available in a bow is equal to the work done in the draw step, that is, it is equal to the product of the traction force, which varies as a function of the draw, multiplied by the variation of the draw itself. By integrating said product over the full draw, the work done and therefore the stored energy are obtained.

In the graphs of FIGS. 42 and 43 the draw is indicated on the abscissa and the force for achieving said draw on the ordinate.

More simply, the work, and therefore the stored energy, is equal to the area subtended by the graph of the traction force as a function of the draw, as can be seen in the graphs of FIGS. 42 and 43.

In the archery sector, maximum traction forces defining size, or capacity, of the bow itself have been defined. In fact, bows of 40 lbs (the measurement unit of reference in this sector are the force-pounds), 50 lbs, 60 lbs etc. are defined; this means that the traction force must never exceed 40 lbs, 50 lbs, 60 lbs, etc.

As a consequence of this, the maximum energy stored by a bow is given by the product of the traction force of reference (40 lbs, 50 lbs, etc.) multiplied by the draw and is represented by a rectangle, for example the rectangle a-b-c-d of FIG. 42.

The graph of FIG. 42 shows, by way of example, the stored energy of a traditional bow. Said energy is represented by the triangle “a-c-d”.

The graph of FIG. 43 shows, by way of example, the energy of a compound bow with cams. With said type of bow, the area of the polygon a-c-d-f″-f tends to be reduced to a scalene trapezoid a-c-d-f as the let-off increases.

As can be seen from what is written above, the usable energy is always a fraction, more or less large, of the maximum obtainable, represented by the area of the rectangle with a base equal to the draw and height equal to the maximum traction force that is typical for the size of the bow.

The compound bow therefore allows to transmit to the arrow a greater amount of energy, therefore greater speed, compared to a traditional bow, with the same load, i.e., a longbow, and to be more accurate in the aiming step.

Said compound bows, although widespread and appreciated, have some limitations.

A first limitation of such known bows consists in the fact that in order to vary the load capacity of a bow beyond a certain range, it is necessary to replace the limbs, where possible, and to adjust the pre-load of the limbs themselves.

Said operations are often cumbersome and therefore difficult to carry out in a short time and without special equipment; above all, the replacement of the limbs requires the availability of other different and adequate limbs and specific equipment for the set-up of the bow with the new limbs.

A second limitation of the known bows consists in the let-off, which despite of having reached good levels nowadays it however involves an important physical effort for the shooter who needs time and stability to aim in the best possible way.

A third limitation of the bows of the known type consists in the structural complexity of the known compound bows, comprising, in addition to the central riser and the limbs, also pulleys, cams or other eccentric elements, double threads placed side by side with the need to adopt a special thread separator, as well as assembly and adjustment components of said components.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a bow-type throwing tool capable of overcoming the aforementioned drawbacks and limitations of the prior art.

In particular, an object of the invention is to provide a bow-type throwing tool that is simpler and faster to calibrate and adjust.

Another object of the invention is to provide a throwing tool with which a better let-off can be achieved with respect to the bows of the known type.

Another object of the invention is to provide a structurally simpler and easier to use bow-type throwing tool.

Another object of the invention is to develop a bow-type throwing tool which has the capability of transmitting a much higher amount of energy to an arrow than known devices already on the market.

The aforementioned task and objects are achieved by a bow-type throwing tool according to claim 1.

Additional features of the bow-type throwing tool according to claim 1 are described in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The task and the aforementioned objects, together with the advantages that will be mentioned below, are highlighted by the description of an embodiment of the invention, which is given, by way of non-limiting example, with reference to the accompanying drawings, wherein:

FIG. 1 represents a side view of a throwing tool according to the invention;

FIG. 2 represents a rear view of the throwing tool of FIG. 1 according to the invention;

FIG. 3 represents a sectional side view of a detail of the throwing tool of FIG. 1;

FIG. 4 represents a side view of the throwing tool according to the invention in an intermediate extension arrangement;

FIG. 5 represents a side view of a detail of FIG. 4;

FIG. 6 represents a detail of FIG. 5;

FIG. 7 represents a side view of the throwing tool according to the invention in a maximum extension arrangement;

FIG. 8 represents a side view of a detail of FIG. 7;

FIG. 9 represents a detail of FIG. 8;

FIGS. 9A and 9B each represent a detail of FIG. 8 in two different operating arrangements of the invention;

FIG. 10 represents a first variant embodiment of the tool according to the invention;

FIG. 11 represents a sectional side view of the first variant embodiment of FIG. 10;

FIG. 12 represents a step of use of the first variant embodiment of the throwing tool according to the invention;

FIG. 13 represents a side view of a second variant embodiment of a throwing tool according to the invention;

FIG. 14 represents a step of use of the tool of FIG. 13;

FIG. 15 represents a variant of a detail of a throwing tool according to the invention;

FIG. 16 represents a section view of the detail of FIG. 15;

FIG. 17 represents a side view of a throwing tool according to the invention in one of its variant embodiments in a rest arrangement;

FIG. 18 represents the same section view as FIG. 17;

FIG. 19 represents a side view of the throwing tool according to the invention in the variant embodiment of FIG. 17, in a maximum extension arrangement;

FIG. 20 represents a side view of a portion of a throwing tool according to the invention in one of its further variant embodiments in a rest arrangement;

FIG. 21 represents a section view of the same side view as FIG. 20;

FIG. 22 represents a front view of the throwing tool in the variant of FIG. 20;

FIG. 23 represents a detail of FIG. 21;

FIG. 24 represents the same section view as FIG. 21 in a final extension arrangement;

FIG. 25 represents a detail of FIG. 24;

FIG. 26 represents a side view of a portion of another variant embodiment of a throwing tool according to the invention;

FIG. 27 represents a sectional side view of the tool of FIG. 26;

FIG. 28 represents a front view of the tool of FIG. 26;

FIG. 29 represents a sectional front view of the tool of FIG. 26;

FIG. 30 represents a sectional side view of a detail of the tool of FIG. 26, in an intermediate operating arrangement;

FIG. 31 represents the same sectional side view as FIG. 30 in a subsequent intermediate operating arrangement;

FIG. 31A represents a detail of FIG. 31;

FIG. 32 represents a detail of FIG. 31;

FIG. 32A represents a detail of FIG. 32;

FIG. 33 represents the same sectional side view as FIG. 30 in an arrangement at the beginning of the unloading step;

FIG. 34 represents a sectional side view of a variant embodiment of the invention;

FIG. 35 represents a front view of a detail of the invention in one of its variant embodiments;

FIG. 36 represents a section view of a portion of the detail of FIG. 35 in a first possible arrangement of use;

FIG. 37 represents a section view of a portion of the detail of FIG. 35 in a second possible arrangement of use;

FIG. 38 represents a section view of a portion of another variant embodiment of the detail of FIG. 35, in a first configuration of use;

FIG. 39 represents a section view of a portion of the variant of FIG. 38, in a second configuration of use;

FIGS. 40 and 41 represent a throwing tool according to the invention in a different structural form;

FIGS. 41A and 41B each represent a section view, respectively in plan and lateral view, of the throwing tool of FIGS. 40 and 41;

FIGS. 42 and 43 represent energy storage graphs referring to archery tools of the known type;

FIGS. 44 to 47 each represent an energy storage graph referring to bow-type throwing tools according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the cited Figures, a bow-type throwing tool according to the invention is indicated as a whole with number 10.

This bow-type throwing tool 10 comprises a central body 11, a nocking string 12 for an arrow, and elastic energy storage means 13 operated by the traction of the string 12.

The peculiarity of the archery tool 10 according to the invention resides in the fact that the means for storing elastic energy 13 comprise:

• • two opposed primary levers 14 and 15 connected with hinging means 16 to the central body 11; the nocking string 12 is constrained by its opposite ends 12a and 12b to opposite free ends 17 and 18 of the primary levers 14 and 15;
  • two opposed axial action thrust accumulators 19 and 20 respectively, defined on the central body 11;
  • loading means 21 of said axial action thrust accumulators 19 and 20, which loading means 21 are configured to induce a compression in the thrust accumulators 19 and 20 following a traction of the nocking string 12.

The central body 11 comprises a part with a predominantly longitudinal development 22.

The part with a predominantly longitudinal development 22 is configured so as to define a handle 23 and an arrow rest area 24.

The central body 11 also comprises two opposite frames 25 and 26 each defining a window, inside each of which windows there is a corresponding thrust accumulator 19 and 20.

The ‘front side’ is defined as the side of the throwing tool 10 turned to the direction of exit of a thrown arrow, and the ‘rear side’ is defined as the opposite side of the same throwing tool 10.

The central body 11 comprises hinging appendages 27 and 28 respectively.

Said hinging appendages 27 and 28 develop from the part of the rear side of the central body 11.

Said hinging appendages 27 and 28 develop from the central body 11 at the frames 25 and 26.

In the present, obviously non-limiting embodiment example of the invention, said hinging appendages 27 and 28 have a trilateral shape.

The nocking string 12 for an arrow can consist of a single thread or alternatively of a braid of threads, and in any case it is to be understood a string of a type known per se.

In the form described herein of the invention, to be understood as an example and not limiting of the invention itself, each of the two opposed primary levers 14 and 15 comprises an ‘L’-shaped body.

Each primary lever 14 and 15 comprises a free end 17 and 18 respectively and an opposite pivoting portion 29 and 30.

Each pivoting portion 29 and 30 is designed for the connection, by means of the hinging means 16, to a corresponding hinging appendage 27 and 28 of the central body 11.

Each primary lever 14 and 15 has a return appendage 17a and 18a respectively, equipped with a rest element 17b and 18b for the nocking string 12 when the throwing tool 10 is in the rest arrangement, as shown in FIGS. 1, 2 and 3.

Said rest element 17b and 18b can consist, for example, of a bearing, or of a simple pin, or other cylindrical or disc-shaped element, fixed or rotatable around its main axis.

The hinging means 16 comprise a pin 31, clearly visible in particular in FIG. 6; said pin 31 is connected to the central body 11, and in particular to the respective hinging appendage 27 or 28, by means of friction reduction means of a type to be understood as known, such as for example two rolling bearings.

In the variant embodiment of the invention described herein by way of non-limiting example of the invention itself, each of the axial action thrust accumulators 19 and 20, respectively, comprises at least one compression load spring.

In particular, in the present embodiment example, an axial action thrust accumulator 19 and 20 comprises a plurality of Belleville springs 40, arranged in series with each other, as clearly visible in FIG. 3.

Still in particular, in the present embodiment example, the thrust accumulator 19 and 20 comprises at least two groups of load springs 40 and 41, for example three groups of load springs 40, 41 and 42.

Advantageously, said groups of load springs 40, 41, 42 have differentiated stiffnesses.

An axial action thrust accumulator 19 and 20 comprises at one end a fixed head 43 and at the opposite end a movable head 44.

The axial action thrust accumulator 19 and 20 comprises a stem 45, translatable in the direction of its own axis X, to which the movable head 44 is constrained.

X is therefore the axis of the stem 45.

The above indicated at least one compression load spring is centrally crossed by a stem; for example, the groups of load springs 40, 41 and 42 are crossed centrally by the stem 45.

The stem 45 has a manoeuvring end 45a, available for the connection to the loading means 21.

The loading means 21, configured to induce a compression in the thrust accumulators 19 and 20 following a traction of the nocking string 12, are hereinafter described as in no way limiting embodiment example of the invention.

Said loading means 21 comprise:

• • a loading thread 47, which is fixed at a first end to the central body 11 and at the opposite second end to a corresponding primary lever 14 or 15;
  • a pulley system configured to cause a translation of the stem 45, for it to exit the frame 25 or 26, i.e., along the line of said axis X and in the compression direction of a corresponding thrust accumulator 19 and 20, following a traction of the loading thread 47.

Said pulley system comprises, for example, two pulleys, a first pulley 48 hinged to the manoeuvring end 45a of the stem 45, and a second pulley 49 hinged to the central body 11.

In particular, the loading thread 47 is fixed at a first end to a fixed pin 50, integral with the central body 11, and at the second end to a movable pin 51, which is instead rotatably constrained to a corresponding primary lever 14 or 15.

The traction of the nocking string 12 by a user causes the simultaneous rotation in a load direction of the primary levers 14 and 15.

The rotation of the primary levers 14 and 15 in the respective load direction causes the rotation of the movable pins 51, each integral with a primary lever 14 and 15, according to a trajectory moving away from the corresponding fixed pin 50.

Said movement of the movable pins 51 causes the traction of the loading threads 47 and, through the pulleys 48 and 49, the translation of the stems 45 for them to exit the respective frames 25 and 26.

The translation of the stems 45 causes the movable heads 44 to move closer to the respective fixed heads 43 of the thrust accumulators 19 and 20 and therefore the loading of the same thrust accumulators 19 and 20.

The thrust accumulators 19 and 20 are said to have an axial action since once they are brought into compression they exert a thrust in the direction of their own main axis X.

In particular, in the present embodiment example, the axial action thrust accumulators 19 and 20 are advantageously coaxial with each other.

The thrust accumulators 19 and 20 each have a single degree of freedom in a direction, which is a vertical direction in the exemplary Figures, indicated by the axis X, of the crushing of the pack of Belleville springs placed in series with each other.

Also each of the primary levers 14 and 15, with respect to the central body 11, has only one degree of freedom, that is it can only rotate around the axis identified by the cylindrical seat where the rolling bearings are housed.

The thrust force exerted by each of the thrust accumulators 19 and 20, i.e., by the compressed Belleville springs described in the present embodiment example, is transmitted from the central body 11 to the primary levers 14 and 15 through the loading thread 47.

Said force tends to rotate the primary levers 14 and 15 towards the front side of the throwing tool 10, opposing a possible rotation of the same primary levers 14 and 15 in the opposite direction.

The rotation of the primary levers 14 and 15 in the direction which is indicated below as the ‘unloading direction’, i.e., towards the front side of the throwing tool 10, ends when the string 12, by resting on the rest elements 17b and 18b, reaches the rest arrangement, as visible in FIGS. 1 to 3.

The nocking string 12 is fixed at its ends to corresponding locking pins 60, which are free to rotate around their axis with respect to the primary lever 14 or 15 which carries them.

The primary levers 14 and 15 rotate until the nocking string 12 is completely drawn as exemplified in FIG. 7.

The load of the springs, partially or completely compressed, creates a tension both on the loading thread 47 and on the nocking string 12.

FIG. 3 shows a first variable lever arm A of the loading string 47 and a second variable lever arm B of the nocking string 12.

By observing the system from this point of view, the primary levers 14 and 15 rotate in the unloading or loading direction according to whether the torque exerted by the thrust accumulators 19 and 20 exceeds or is less than the torque exerted by the nocking string 12.

FIGS. 4 to 6 show an intermediate arrangement of use of the throwing tool 10 according to the invention.

In said intermediate arrangement, the nocking string 12 is pulled with a force applied at the nocking point P, to be understood as positioned halfway of the nocking string

The torque exerted by the nocking string 12, pulled at point P by the hand of a user, possibly by means of suitable tools of the known type called in the sector with the term ‘releases’, on each of the primary levers 14 and 15, is higher than the torque achieved by the thrust accumulators 19 and 20, whereby the primary levers 14 and 15 rotate in the loading direction, whereby the moving away of the nocking point P from the central body 11 is favoured.

The stems 45 of the thrust accumulators 19 and 20 tend to be extracted from the respective frames 25 and 26, moving towards the respective maximum extraction position. Consequently, the Belleville springs, stacked in series on said stems 45, tend to become more and more crushed, increasing more and more the amount of elastic energy stored.

The variable lever arms A and B vary as a function of the rotation of the corresponding primary lever 14 or 15; in particular, the first lever arm A, of the loading thread 47, tends to decrease while the second variable lever arm B, of the nocking string 12, tends to increase, as clearly visible by comparing FIGS. 3, 4 and 6, with a multiplier effect that allows storing a high level of elastic energy when compared to the shooting force at point P of the nocking string 12.

FIGS. 7 to 9 show the throwing tool 10 according to the invention in its maximum extension arrangement.

In said arrangement, the primary levers 14 and 15 have reached their respective final position of maximum load; in fact, each lever 14 and 15 rests against a striker portion 11 a of the central body 11, therefore it cannot rotate further in the loading direction, regardless of the force achieved on the nocking string 12.

The stem 45 of each accumulator 19 and 20 has reached the maximum design extraction position and the relative springs 40, 41 and 42 reach their maximum rated design compression and, consequently, exert their maximum design force.

The variable lever arms, first arm A of the loading string 47, clearly visible in FIG. 9, and second arm B of the nocking string 12, indicated in FIG. 7, reach their final size at completion of the design draw.

A notch 31a is made on said pin 31 for the passage of the loading thread 47, said notch 31a being configured to allow the progressive reduction of the distance between the axis X47 of the loading thread 47 and the rotation axis X31 of said pin 31 during the traction step of the nocking string 12.

The pin 31, at the notch 31a, has a solid part 31b configured to define a curved surface 31c for the rest of the loading thread 47.

Hence, the notch 31a is concave and the solid part 31b of the pin 31 is correspondingly convex.

The curved surface 31c has a cusp 31d.

The axis X31 of the pin 31 crosses the pin 31 at the notch 31a, and not at the solid part 31b.

The distance between the axis X47 of the loading thread 47 and the rotation axis X31 of the pin 31 is indicated in FIG. 9B with the symbol D and corresponds, that is coincides, to the variable lever arm A described above.

The distance between the cusp 31d and the rotation axis X31 of the pin 31 is indicated with the symbol Z, as shown in FIG. 9A.

Said distance Z is less than the radius of the loading thread 47.

In particular, and by way of example, said notch 31a is shaped in such a way that the axis X47 of the loading thread 47 stops at a distance D from the axis X31 of the pin 31 which can be comprised between 1 and 5 hundredths of a millimetre.

The distance D between the axis X31 of the pin 31 and the axis X47 of the loading thread 47 corresponds to the difference between the radius of the loading thread 47 and the distance Z between the cusp 31d and the axis X31 of the pin 31.

Said notch 31a develops like an arc of a circle over an angle comprised between 180° and 200°, and in general greater than 180°.

In particular, therefore, the distance D of the axis X47 of the loading thread 47 from the rotation axis of the pin 31 is near zero, remaining greater than zero, to allow the rotation in the unloading direction once the force generating the draw has been zeroed, that is when the user releases the string 12.

Said situation occurs thanks to the notch 31a made on the rotation pin 31 of each primary lever 14 and 15, and clearly visible in FIGS. 6, 9, 9A and 9B, so that, when a primary lever 14 and 15 is in the arrangement of maximum extension of the throwing tool 10, the axis X47 of the loading thread 47 almost intersects the rotation axis X31 of the pin 31. Furthermore, the notch 31a is made in such a way that the distance of the axis X47 of the loading thread 47 from the rotation axis X31 of the pin 31 is always greater than zero. In fact, the loading thread 47 rests on the cusp 31d of the notch 31a which is at a distance, from the rotation centre, less than the radius of the loading thread 47 itself, thus ensuring that the distances between the axes are always greater than zero.

In this way the torque exerted by the loading thread 47 on the primary lever 14 does not change its sign.

Once the draw force has been zeroed, when the arrow nocked on the string 12 is released, the torque achieved by the nocking string 12 is equal to zero while the force of the axial action thrust accumulators 19 and 20 is greater than zero, and therefore the levers 14 and 15 move in the unloading direction, shifting to the rest arrangement of FIGS. 1, 2 and 3.

The combination of the variable lever arms A, i.e., the distance D, and B during the loading step is such that, depending on the draw, the force necessary to achieve said draw has a trend represented by the graph shown in FIG. 44, where the abscissa shows the draw in millimetres and the ordinate the force for achieving said draw expressed in Newton.

Said trend is an example, since numerous variants of the trend of the graph shown in FIG. 44 are possible, as for example in the graphs of FIGS. 45 and 46. Each of said graphs is to be intended as referring to a single thrust accumulator 19 and 20, and not to the total energy storage achieved by both thrust accumulators operated simultaneously during a draw.

Said trend shows that the let-off at the maximum draw is very low and the reduction in the loading effort is reduced by more than 90%.

The thrust accumulators 19 and 20 of the invention lead to the following advantages:

• • thanks to the coaxial and opposed position, at the end of the return stroke the blocking forces of the two accumulators 19 and 20 are opposed and cancel out each other; in this way, the perturbation on the system, when the end of stroke is reached, is much reduced;
  • in the bows with known limbs, the load on the bow can be varied either by replacing the limbs, thus switching from a predefined level to another one, or by adjusting their pre-load; thanks to the throwing tool 10 according to the invention, by varying the type and size of the load springs that make up the accumulators 19 and 20, it is possible to vary the load gradually, and by varying the amount of the springs it is possible to obtain a graph of more personalized load;
  • the possible breakage of a spring allows in any case the operation of the throwing tool 10, contrary to the bows with limbs of the known type;
  • the pre-load, or the load on the loading thread 47 in the rest configuration, can be easily varied by acting on a nut 80 which closes the springs on the stem 45.

As mentioned above, the first variable lever arm A of the loading thread 47 is determined by the distance between the axis of the loading thread 47 itself and the axis of the unloaded pin 31 of the corresponding primary lever 14 or 15.

In the example described and illustrated herein, the unloaded pin 31 rotates integrally with the primary lever 14 or 15, but alternatively the pin 31 can be integral with the central body 11. In this case, the lever 14 and 15, equipped with suitable bearings, would rotate around its own pin 31.

The variable lever arm A of the loading thread 47 is reduced to almost zero when the lever 14 and 15, by rotating, reaches the position of maximum draw. This occurs because the loading thread 47 is fixed to a movable pin 51 which is integral with the lever 14 and 15 itself.

As the lever 14 and 15 rotates, the movable pin 51 rotates around the rotation centre of the pin 31 of the lever 14 and 15, shifting to a position such that the axis of the loading thread 47 almost coincides with the rotation axis.

The notch 31a of the pin 31, in addition to allowing the lever arm to be almost zeroed, ensures that this is always greater than zero. In fact, the mechanical machining of the unloaded surface of the notch 31a is done in such a way that the distance between the cusp and the rotation axis is less than the radius of the loading thread 47 itself.

Said configuration makes it possible to reach final load reductions, i.e., ‘Let-Off ratio’ values that are higher than those of the systems on the market.

As mentioned above, each of the primary levers 14 and 15 is connected to the central body 11 by means of the unloaded pin 31, which rotates rigidly with the respective lever 14 and 15, and by means of two rolling bearings which allow the rotation of the lever with a friction close to zero.

The rolling bearings are connected on one side to the lever 14 or 15 while on the other side they are connected to a seat defined on the central body 11, for simplicity not illustrated. Between the seat on the central body 11 and the bearing there is a rubber body, for example one or more O-rings, for example made of NBR plastic; the presence of such rubber bodies has the following advantages:

• • it reduces the vibrations generated by the nocking string 12 when it is released and it returns to the rest configuration after the loading step;
  • it reduces the machining cost of the seat of the bearing because the tight coupling tolerances that are typical of the bearing seats are not required.

‘Draw Length’ means the distance between the handle and the nock point of an arrow.

The final position of the primary levers 14 and 15 is defined by the design, since the central body 11 has, as mentioned, a striker portion 11 a which blocks the rotation of the levers 14 and 15 themselves.

From this point, the desired draw is obtained by selecting the length of the nocking string 12.

In current systems, the definition of the draw is achieved by means of a cam device with discrete adjustments which allows, with the same components, to obtain a limited adjustment interval of the draw.

Sometimes such adjustment requires using a dedicated tool, known as a ‘bow press’, to modify the attachment position of the nocking string.

With the present invention, by simply modifying the length of the nocking string 12 it is possible to obtain an almost continuous variation of the draw from a maximum to a minimum value (said values are related to the size of the primary levers 14 and 15).

Furthermore, discretised variations in draw can be obtained by using the same nocking string 12.

This is achieved, as exemplified in the variant embodiment of FIGS. 10, 11 e 12, by means of a draw discretisation insert 90.

Said draw discretisation insert 90 is fixed in a hole 91x chosen from a plurality of aligned holes 91 defined on each of the primary levers 14 and 15.

By keeping the same nocking string 12 with predetermined length, and simply choosing a hole 91x and fixing the string 12 to the draw discretisation insert 90 and then the insert to the hole 91x, it is possible to modify the performance of the throwing tool 10 in numerous ways according to the user's needs and technical requirements.

In a variant embodiment of the throwing tool according to the invention, not illustrated for simplicity, the loading thread and the nocking string are both made of a single thread or of a single string.

The throwing tool 10 according to the invention allows making a very wide and refined variation of the load curve.

In particular, while the current technology allows a percentage of lightening of the shot in the final position (Let-Off) in the range 70÷90%, the throwing tool 10 according to the invention allows to easily reach a let-off higher than 90%, thus guaranteeing to the archer a greater relaxation during the aiming step before shooting the arrow.

A further advantage achieved by the throwing tool 10 according to the invention is given by the fact that the configuration of the same throwing tool 10 allows to eliminate the cables connecting the pulleys thus allowing greater visibility and better manoeuvrability for the archer.

Furthermore, the throwing tool 10 according to the invention does not require the use of dedicated systems, such as adjustment benches—bow press, for adjusting the bow shot and the draw thereof.

Furthermore, with the throwing tool 10 according to the invention, the configuration of the load graph can be easily adapted to the needs of the archer by acting, as already said, on the configuration of the accumulators 19 and 20, i.e., of the packs of Belleville springs.

Furthermore, by acting on the pulleys 48 and 49 and on the other mechanical members of the mechanism of the loading thread 47 the desired let-off can be obtained.

The same variation in let-off can be obtained by varying the final, end-of-stroke, position, of the levers 14 and 15.

As mentioned above, the variation of the draw of the throwing tool 10 can be made in two ways:

• • by varying the length of the nocking string 12, choosing a string 12 having the preferred length;
  • by using the draw discretisation insert 90; by varying the position of said draw discretisation insert 90 in the holes 91, with the same length of the thread, the draw varies in a discrete manner.

In a variant embodiment of the invention, the axial action thrust accumulators 119, so indicated in FIGS. 15 and 16, are of the magnet type.

Such magnet thrust accumulators 119 have two magnets or electromagnets 140 and 141, one of which fixed to a fixed head 143 and the other one movable and resting on a movable head 144; the movable head 144 is fixed to the stem 145 which is in turn translated by the loading means 21, as described above.

By placing the magnetic poles in opposition and moving them closer against each other it is possible to achieve the same dynamic action done by the springs.

In a further variant embodiment of the invention, exemplified in FIGS. 13 and 14, each of the ends of the nocking string 12 is fixed to an intermediate rod 99, which in turn is pivoted to a corresponding locking pin 60, as above described.

Said intermediate rod 99 has such a length so as to rest on the rest element 17b and 18b of the respective primary lever 14 and 15 in the rest arrangement.

Said intermediate rod 99 is rigid.

The application of said intermediate rod 99 allows the adoption of a shorter, therefore less expensive, nocking string 12 and also reduces the vibrations of the nocking string 12 itself.

In a further variant embodiment of the invention, illustrated below, the bow-type throwing tool comprises a crossbow-like structure, that is also comprising a gripping shaft, known in the jargon of the sector as a ‘tiller’, and loading and release mechanisms for a body to be thrown.

FIGS. 17 to 19 show a different variant embodiment of the throwing tool according to the invention, indicated therein as a whole with number 110.

In said variant embodiment, it being also obviously exemplary and non-limiting of the invention itself, each of the two opposed primary levers 114 comprises a circular sector shaped body.

Each primary lever 114 comprises a pivoting portion 129 defined at the axis of the profile of the circular sector shaped body.

Each pivoting portion 129 is designed for the connection, by means of the hinging means 16 as described above, to a corresponding hinging appendage 27 of the central body 11, similarly to what has already been described for the previous variant embodiment of FIGS. 1 to 16.

Each primary lever 114 has a curved perimeter edge 117a, provided with a rest groove 117b for the nocking string 12 when the throwing tool 110 is in the rest arrangement, as shown in FIGS. 17 and 18.

Similarly to what has been described above, the loading thread 47 is fixed at a first end to a fixed pin 50, integral with the central body 11, and at the second end to a movable pin 151, which is instead rotatably constrained to a corresponding primary lever 114.

Also in said variant embodiment the throwing tool 110 comprises a draw discretisation insert 190.

Said draw discretisation insert 190 is fixed in a hole 191x chosen from a plurality of aligned holes 191 defined on the curved perimeter edge 117a of each of the primary levers 114.

The operation of said variant embodiment is analogous to the operation of the variants described above.

As can be seen from what is written above, the usable energy is always a fraction, more or less large, of the maximum obtainable energy, represented by the area of a rectangle having a base equal to the draw and height equal to the maximum traction force that is typical for the size of the throwing tool.

To obtain more energy, it is necessary to approximate the area of the rectangle described above as much as possible and, finally, to obtain an energy greater than the area itself, it is necessary to store mechanical energy in advance to be released then when the arrow is released.

Two systems have been developed to meet said needs. A first system, exemplified in FIG. 20, optimises the approximation of the area of the rectangle. A second system, exemplified in FIG. 26, stores in advance mechanical energy.

Both systems are configured in such a way that the stored energy is released to the arrow, together with that of the thrust accumulator 19 and 20, when it is released upon completing the draw.

Therefore, in a variant of its embodiment shown in Figures from 20 to 25, the bow-type throwing tool 210 according to the invention also comprises a pair of load increase devices 261, configured to operate in series with a corresponding thrust accumulator 19 and 20.

The Figures show, by way of example, only one of said load increase devices 261, whereby the other opposite load increase device not shown is intended as being equal.

Said load increase device 261 comprises:

• • a stem 245 of the thrust accumulator 19, which is equipped with a striker head 262,
  • a containment box 263, fixed externally to the end of the frame 25,
  • a slider body 264 placed so as to translate, along the thrust axis X of the corresponding thrust accumulator 19, into a through hole 265 defined at the end of the frame 25 and into a coaxial guide hole 266 defined in the containment box 263,
  • a plurality of thrust increase springs 267 and 268, placed so as to act between a cover 269 of the containment box 263 and a shoulder 270 of the slider body 264.

The slider body 264 also comprises an abutment element 271, configured to abut against the striker head 262 of the stem 245.

Said abutment element 271 is configured to be able to adjust the axial position with respect to the slider body 264 itself, with the aim of defining the distance with the striker head 262.

The abutment element 271 consists for example of a screw screwed axially to the slider body 264.

Alternatively, the abutment element 271 can be fixed permanently to the slider body 264 or it can also be made in a single piece with the slider body 264.

The containment box 263 comprises the cover 269 and a spacing side wall 272.

The cover 269 is fixed to the end of the frame 25 by means of threaded connections 269a of a type known per se.

Said load increase device 261 works as follows.

When the user pulls the nocking string 12, the stem 245 translates, pulled by the loading thread 47, until it abuts against the abutment element 271; afterwards, the traction by the user causes the thrust of the stem 245 on the slider body 264 and the consequent compression of the increase springs 267 and 268, with a further storage of throwing energy in the same increase springs 267 and 268, as exemplified in the FIGS. 24 and 25.

When the user releases the nocking string 12, a thrust force is transmitted to the primary lever 214 which force comprises both the action of the springs of the thrust accumulator 19 and the action of the increase springs 267 and 268 of the load increase device 261.

The load increase device 261 can also comprise a stroke limiter 273 for limiting the stroke of some of the increase springs 267 and 268.

For example, said stroke limiter 273 consists of a cup comprising a disc base 273a and a cylindrical wall 273b in which some increase springs 268 are housed, the stroke of which is to be limited, thus adjusting the action of the same.

In fact, during the crushing step of the increase springs 268 the cylindrical wall of the stroke limiter 273 will rest against the cover 269, preventing the increase springs 268 contained in the stroke limiter 273 itself from being further crushed.

FIG. 45 shows a graph in which the draw in millimetres is indicated on the abscissa and the force for achieving said draw expressed in Newtons on the ordinate; in this graph a dashed line indicates a pull curve in the absence of the load increase device 261, while a solid line indicates a pull curve in the presence of the load increase device 261

In a further variant embodiment shown in Figures from 26 to 34, the bow-type throwing tool 310 according to the invention also comprises a pair of pre-loadable external auxiliary accumulators 361 configured to operate in series with a corresponding thrust accumulator 19 and 20.

In this way an energy higher than that represented by the Pull-Draw rectangle is obtained.

The Figures show, by way of example, only one of said pre-loadable external auxiliary accumulators 361, whereby the other opposite pre-loadable external auxiliary accumulator not shown is intended as being equal.

Said pre-loadable external auxiliary accumulator 361 comprises:

• • a stem 345 of the thrust accumulator 19, which is equipped with a striker head 362;
  • a containment box 363, fixed externally to the end of the frame 25;
  • a first slider body 364A placed so as to translate, along the thrust axis X of the corresponding thrust accumulator 19, into a through hole 365 defined at the end of the frame 25;
  • a second slider body 364B placed so as to translate, along the thrust axis X, into a guide hole 366a defined on the first slider body 364A and into a coaxial guide hole 366b defined in the containment box 363;
  • a plurality of thrust increase springs 367, placed so as to act between a cover 369 of the containment box 363 and a first shoulder 370 of the second slider body 364B; said thrust increase springs 367 are, for example, Belleville springs;
  • a pre-load lever 381, pivoted to a bracket 382, developing from the cover 369, through a pin 383;
  • a pre-load tie rod 384 constrained at a first end 384a to a first traction pin 385 fixed to the second slider 364B, and at the opposite second end 384b to a second traction pin 386 fixed to the pre-load lever 381; the pre-load tie rod 384 for example consists of a flexible element, for example a cord, with two opposite end slots; the end slots allow the swivel constraint with the pins 385 and 386; alternatively, said pre-load tie rod consists of a rigid element;
  • an elastic return element 387 constrained on one side to the cover 369 and on the opposite side to the pre-load lever 381; said elastic return element 387 is, for example, a helical spring operating in traction.

The pre-loadable external auxiliary accumulator 361 can comprise, like in the embodiment example from FIG. 26 to FIG. 33:

• • one or more accompanying springs 368, placed so as to act between the first shoulder 370 of the second slider body 364B and a facing second shoulder 370a of the first slider body 364A; said accompanying springs 368 are, for example, Belleville springs; the

Figures show a single accompanying spring 368, but it is to be understood that there may also be two or more;

• • a stroke adjustment system for said accompanying springs 368, defined below by way of example by the striker perimeter wall 370b, clearly visible in FIGS. 31 and 33, of the first slider body 364A.

The pre-load lever 381 can be manoeuvred by means of a manoeuvring rod 388, reversibly inserted in a corresponding fixing hole 381a defined on the same pre-load lever 381

The first slider body 364A also comprises an abutment element 371, configured to abut against the striker head 362 of the stem 345.

Said abutment element 371 is configured to be able to adjust its own axial position with respect to the first slider body 364A itself and with the aim of defining the distance with the head 362.

The abutment element 371 consists for example of a screw screwed axially to the first slider body 364A.

Alternatively, the abutment element 371 can be fixed permanently to the slider body 364, or it can also be made in a single piece with the slider body 364.

The containment box 363 comprises the cover 369 and a spacing side wall 372.

The cover 369 is fixed to the end of the frame by means of threaded connections 369a of a type known per se.

The configuration of a pre-loadable external auxiliary accumulator 361 in a non-loaded arrangement is shown in FIGS. 26, 27 and 29.

In said arrangement, the draw is equal to zero and the group comprising the pre-load lever 381, the elastic return element 387, the pre-load tie rod 384 and the thrust increase springs 367, is in the rest position.

In said arrangement, in particular, the pre-load lever 381 is rotated to the right, with respect to the representation of FIGS. 26 and 27, the elastic return element 387 exerts a very small or null force and the thrust increase springs 367, as well as the accompanying springs 368, are completely unloaded and therefore open, in the sense of “not compressed”.

In said non-loaded arrangement, the adjustment screw with the abutment element 371 is positioned at a distance established by the head 362 of the stem 345. In said configuration, the removable manoeuvring rod 388 is inserted in its fixing hole 381a on the pre-load lever 381.

The loading step is represented in FIGS. 28, 30, 31 and 33.

Loading takes place by applying a force on the manoeuvring rod 388, removable, so as to cause a torque capable of rotating the pre-load lever 381 anticlockwise with reference to FIGS. 30 and 31 with respect to its pin 383.

Said rotation, starting from the rest position of the load-absent arrangement described above, tends to displace the second traction pin 386, integral with the pre-load lever 381, moving it away from the end of the frame 25; said displacement of the second traction pin 386 causes a displacement in the axial direction X of also the first traction pin 385 being moved away from the end of the frame 25, which displacement is caused by the pre-load tie rod 384 which connects the two traction pins 385 and 386.

The first traction pin 385 is, in turn, rigidly connected to the second slider body 364B, which is translated in the same way.

The movement, along the axis X, of the second slider body 364B being moved away from the end of the frame 25 in turn causes the crushing of the thrust increase springs 367 which cannot move vertically as they are resting, possibly by means of an adjustment shim 389, on the cover 369; the cover 369 supports the pre-load lever 381 and is rigidly fixed to the spacing walls 372 and to the frame 25 which in turn is part of the central body 11.

The crushing of the springs generates an elastic force transmitted to the pre-load lever 381 through the pre-load tie rod 384.

The mutual position of the pin 383 of the pre-load lever 381, of the first traction pin 385 and of the second traction pin 386 is such that, in the non-load arrangement, the longitudinal axis of the pre-load tie rod 384 is located, with respect to the Figures, on the right side of the rotation axis of the pin 383 of the pre-load lever 381, as shown in FIGS. 26 and 27.

The pin 383 is positioned with an axis parallel to the axis of the first traction pin 385.

The axes of said pin 383 and of said first traction pin 385 lie on the same plane passing through the axis X; the axes of the pin 383 of the pre-load lever 381 and of the first traction pin 385 are therefore aligned in the direction of the axis X of action of the thrust accumulators 19 and 20.

Said elastic force therefore generates a torque, which opposes the rotation of the pre-load lever 381, equal to the product of the distance of the axis of the pre-load tie rod 384 from the rotation centre of the pin 383, multiplied by the elastic force itself. Naturally, in order to continue the loading step, the torque exerted through the removable manoeuvring rod 388 must be higher than the resistant one exerted by the tie rod 384.

When the tie rod 384 is with its axis aligned with the line joining the rotation centres of the two pins 383 and 385, there is a configuration of maximum crushing of the springs during the loading step; in such an arrangement of maximum crushing of the springs the resistant torque is null since the arm of the torque is null; the torque caused by the elastic return element 387 is neglected because it is very low in said arrangement.

Continuing the anticlockwise rotation, through the force applied to the removable manoeuvring rod 388, the axis of the pre-load tie rod 384 switches from the position of null arm to a position inclined towards the left, always with reference to the relative Figures.

In said arrangement, the torque exerted by the force of the springs tends to accelerate the anticlockwise rotation, lowering the height of the second upper traction pin 386 and of all the elements connected thereto.

The anticlockwise rotation of the pre-load lever 381 is interrupted when the same pre-load lever 381 abuts against a stop end element 390; said stop end element 390 consists, for example, of a flat appendage which develops from the cover 369 and is integral therewith.

The pre-load lever 381 has a rest tooth 381b configured to abut against the stop end element 390.

At this point, the removable manoeuvring rod 388 can be removed and the external auxiliary accumulator 361 assumes the configuration shown in FIG. 30.

The elastic return element 387, switching from the non-load arrangement to the load arrangement, undergoes an elongation and therefore generates a force, clockwise, which tends to return the pre-load lever 381 to the initial non-load arrangement.

The torque generated by the force of the elastic return element 387 is however much lower than the torque, operating in an anticlockwise direction, caused by the pack of thrust increase spring 367 through the pre-load tie rod 384, whereby the pre-load lever 381 remains blocked in said holding arrangement.

The stored pre-load energy, in said step, is equal to the work done to deform all the pre-load springs.

It should be noted that the whole action described above does not affect the accompanying spring 368, if present, and the relative first slider body 364A; in fact, their position remains unchanged like all the other components of the archery tool 310, i.e., the main lever 314, the loading thread 47, the nocking string 12 and the thrust accumulators 19 and 20.

The step for releasing the energy stored in the thrust increase springs 367, as well as the action of one or more accompanying springs 368 are described below.

In said release step, a user begins to load an arrow nocked on the nocking string 12, increasing the draw and bringing it to its maximum value.

As a consequence thereof, the primary lever 314 starts rotating around the rotation axis of the rotation pin 31.

The loading thread 47, with one end integral with the primary lever 314, is pulled and this causes the part of the thread engaged between the fixed pin 50 and the second pulley 49 to shorten; as a consequence there is a traction, through the first pulley 48, of the stem 345 in the direction of the axis X, the head 362 of which moves towards the abutment element 371 of the first slider body 364A.

At a certain draw and, therefore, at a certain rotation of the primary lever 314, the head 362 of the stem 345 reaches the abutment element 371.

By continuing to increase the draw, the stem 345 translates further, further pushing the first slider body 364A outwards, in the direction of the axis X.

The stem 345 further translates, further pushing outwards, in the direction of the axis X, the first slider body 364A together with the accompanying spring 368, when the latter is present, until the same accompanying spring 368 touches the lower surface of the first shoulder 370, as shown in FIG. 31.

The second slider body 364B is pushed towards the centre of the central body 11 by the force of the thrust increase springs 367 and is held in said position by the pre-load tie rod 384.

The force of the thrust increase springs 367 is much higher than the one exerted by the accompanying spring 368, and consequently, by continuing to increase the draw, the stem 345 continues to rise by crushing the accompanying spring 368 against the lower surface of the second slider body 364B. Said crushing continues until the first slider body 364A rests on the lower surface of the second slider body 364B.

The stroke adjustment system for the accompanying springs 368 comprises one or more striker perimeter walls 370b, fixed, or alternatively resting, to the second shoulder 370a of the first slider body 364A, as clearly visible in FIG. 31; the stroke adjustment system can comprise a single continuous perimeter wall or several perimeter walls spaced apart from each other along the same perimeter.

The one or more striker perimeter walls 370b are configured to abut against the first shoulder 370 of the second slider body 364B and therefore to limit the crushing of one or more accompanying springs 368.

At this point, the further increase in the draw and the consequent further translation of the rod 345 outwards in the direction of the axis X cause a further crushing of the thrust increase springs 367 in addition to that defined by the action of the pre-load lever 381 through the tie rod 384.

In said arrangement, the imposed draw has not been reached yet and consequently the primary lever 314 must still rotate to reach it, i.e., the axis of the loading thread 47 is at a certain distance from the axis of the pin 31 of the primary lever 314.

To reach the established draw, the nocking string 12 is to be further pulled, with consequent rotation of the primary lever 314 which rotates until it is blocked against a stop end. This obviously involves a further translation of the stem 345 together with the second slider body 364B and a consequent further crushing of the thrust increase springs 367.

When the distance between the first traction pin 385, integral with the second slider body 364A, and the second traction pin 386, integral with the pre-load lever 381, is smaller than the length of the pre-load tie rod 384, the pre-load tie rod 384 is loose, stops operating in traction and consequently the whole force, exerted by the thrust increase springs 367, is supported by the rod 345.

Said increase in thrust is transferred to the nocking string 12 through the loading thread 47 and the primary lever 314, with a consequent increase in the shooting force.

Said increase in the shooting force is in any case within the size of the archery tool itself, because the transfer of the force exerted by the thrust increase springs 367, very high, occurs when the distance of the axis of the loading thread 47 almost coincides with the rotation axis of the rotation pin 31, as described above with regard to the pin 31, and this greatly reduces the resistant torque that must be overcome by the torque achieved by the nocking string 12.

In said configuration, the torque which pushes the pre-load lever 381 against the stop end element 390 is cancelled out, since the force is supported by the stem 345 and, consequently, the torque exerted by the return elastic element 387 no longer finds opposition.

The pre-load lever 381 then starts a clockwise rotation towards the starting non-load arrangement.

In order to complete the rotation, the pre-load lever 381 must surpass the vertical and this happens when the extra-stroke, indicated with “F” in FIG. 31 and FIG. 31A, of the stem 345 exceeds the distance according to the vertical direction, between the rotation centre of the second traction pin 386 in the end-of-stroke arrangement and the rotation centre of the same second traction pin 386 when it is aligned with the rotation centre of the first traction pin 385 and the pin 383 of the pre-load lever 381, said distance being indicated with “L” in FIG. 32 and in FIG. 32A, and being detected along a direction parallel to said straight line of alignment of the rotation centres of the pins 386, 385 and 383.

FIG. 46 shows a graph in which the draw in millimetres is indicated on the abscissa and the force for achieving said draw expressed in Newtons on the ordinate; in said graph, a dashed line indicates a shooting curve in the absence of the pre-loadable external auxiliary accumulator 361, while a solid line indicates a shooting curve, in the loading step, in the presence of the pre-loadable external auxiliary accumulator 361.

The pre-load tie rod 384, being flexible, adapts to said new configuration as shown in FIG. 33, where the pre-load lever 381 has completed the clockwise rotation.

By releasing the nocked arrow, the thrust increase springs 367, together with the accompanying spring 368 when present, push the stem 345 towards the centre of the central body 11, so do also the springs of the thrust accumulator 19; in this way, the energy received by the arrow is equal to that of the springs of the thrust accumulator 19 added to that of the thrust increase springs 367, and to that of the accompanying spring 368, or of the accompanying springs 368 if more than one are present.

FIG. 47 shows a graph in which the draw in millimetres is indicated on the abscissa and the force for achieving said draw expressed in Newtons on the ordinate; in said graph, a dotted line indicates a return curve in the absence of the pre-loadable external auxiliary accumulator 361, while a solid line indicates a return curve in the presence of the pre-loadable external auxiliary accumulator 361.

FIG. 34 shows a variant embodiment of a pre-loadable external auxiliary accumulator 461 without the accompanying spring 368.

In this case, however, the trend of the shooting force may be unwelcome to the archer who, at the end of the draw, would have a peak load.

The advantage that is obtained by adding one or more accompanying springs 368 is that of avoiding an instantaneous overload to the nocking string 12, and therefore to the user's hand, when the elastic return element 387 releases the thrust increase springs 367.

Both with the application of a pair of load increase devices 261, and with the application of a pair of pre-loadable external auxiliary accumulators 361, an increase in the stored energy is obtained.

Furthermore, the ratio between stored elastic energy and maximum shooting force is approximately double the one currently declared by the current technology, which allows increasing the performance with the same effort for the archer or reducing the effort for the archer with the same performance, facilitating, for example, the resistance in shooting competitions.

These solutions can be adopted in a performing way because at the end of the draw the lever arm that is formed between the axis of the loading thread 47 and that of the rotation pin 31 is close to zero. Consequently, the force due to the deformation of the thrust increase springs 267 and 367 can be very high and this entails a high storage of energy without there being an appreciable increase in the shooting effort required to the archer. FIGS. 35 to 37 describe a variant embodiment of a thrust accumulator, indicated therein as a whole with the number 419.

Like for the axial action thrust accumulators 19 and 20 described above, the thrust accumulator 419 comprises at least one compression load spring, for example a plurality of Belleville springs 440, arranged in series with each other, as clearly visible in FIG. 3.

Still in particular, in the present embodiment example, the thrust accumulator 419 comprises two groups of load springs 440 and 441.

An axial action thrust accumulator 419 comprises at one end a fixed head 443 and at the opposite end a movable head 444.

The axial action thrust accumulator 419 comprises a stem 445, translatable in the direction of its own axis X, to which the movable head 444 is connected.

The stem 445 has a manoeuvring end 445a, available for the connection with the loading means 21.

In particular, the stem 445 comprises, at the manoeuvring end 445a, the first pulley 48 of the loading means 21.

In said particular variant embodiment, the thrust accumulator 419 comprises a stroke adjustment system 492, configured to limit the crushing of one or more springs, for example a group of springs 441.

Said technical solution, described for a thrust accumulator indicated with 419, is to be understood to be applicable also to the thrust accumulators described above and indicated with 19 and 20.

Said stroke adjustment system 492 comprises a cup-shaped body 493, resting on the movable head 444 and free to translate therewith along the stem 445.

Said cup-shaped body 493 has a base 494 and a side wall 495 for limiting the stroke.

Said side wall 495 has a variable height.

For example, this side wall 495 is connected to the base 494 by means of a threaded connection 496.

The stroke adjustment system 492 also comprises an end-of-stroke disc 497 arranged between the two groups of springs 440 and 441, which is configured to abut against the side wall 495 of the cup-shaped body 493 causing the compression of the group of springs 441 contained in the cup-shaped body 493 to stop.

The springs 441, of which the stroke is to be limited, thus adjusting the action of the same, are housed between the stem 445 and the side wall 495.

In fact, in the crushing step of the springs 441, the side wall 495 of the stroke limiter rests on the end-of-stroke disc 497, preventing the springs 441 themselves from being further crushed.

The height of the side wall 495, and therefore the stroke of the springs 441, can be varied continuously.

FIG. 36 shows a thrust accumulator 419 with the side wall 495 already arranged in contact with the end-of-stroke disc 497, in an arrangement which prevents the springs 441 from being crushed.

In FIG. 37 the side wall 495 is lowered and spaced from the end-of-stroke disc 497, in which case therefore a certain compression is allowed to the springs 441 until the side wall 495 abuts against the end-of-stroke disc 497.

Another stroke adjustment system 592 is shown in FIGS. 38 and 39, in relation to a thrust accumulator 519.

In said stroke adjustment system 592, the side wall 595 of the cup-shaped body 593 is fixed to the base 594.

A calibrated shim 598 may be present inside the cup-shaped body 593, as clearly visible in FIG. 39.

By positioning or removing the calibrated shim 598, or by replacing a calibrated shim 598 with another calibrated shim with different height, the stroke and the degree of pre-compression of the springs of the thrust accumulator 519 are modified, with respect to the end-of-stroke disc 597.

FIGS. 40, 41, 41A and 41B show an archery tool 610 configured as a crossbow, it also to be understood as the object of the invention.

Said throwing tool 610 comprises a central body 611 from which a tiller 611a, a nocking string 612 for a dart and elastic energy storage means operated by the traction of the string 612 develop.

The peculiarity of the archery tool 610, of the crossbow type, according to the invention resides in the fact that the elastic energy storage means comprise:

• • two opposed primary levers 614 and 615 connected with respective hinging means 616 to the central body 611; the nocking string 612 is constrained by its opposite ends 612a and 612b to opposite free ends 617 and 618 of the primary levers 614 and 615;
  • an axial action thrust accumulator 619, defined on the tiller 611a;
  • loading means 621 of said axial action thrust accumulator 619, which loading means 621 are configured to induce a compression in the thrust accumulator 619 following a traction of the nocking string 612.

The thrust accumulator 619 is to be intended as the same or analogous to one of the thrust accumulators 19, 119, 419, 519 described above.

As described above for the archery tool 10, a frame 625 defining a window is defined on the tiller 611a, inside which window the thrust accumulator 619 is placed.

Also the loading means 621 are to be intended as similar and equivalent to the loading means 21 described above, with a loading thread 647 and a pulley system configured to cause a translation of the stem 645 of the thrust accumulator 619, as described above for the other variant embodiments of the invention.

The thrust accumulator 619 and the loading means 621 are mounted on the tiller 611a.

Also in said embodiment of the invention, the hinging means 616 comprise, for each primary lever 614 and 615, a pin 631, corresponding to the pin 31 described above, a notch 31a being made on said pin 631 for the passage of the loading thread 647.

In particular, in the present embodiment example, the pulley system, configured to cause a translation of the stem 645, comprises four pulleys, a first pulley 648 pivoted to the manoeuvring end 645a of the stem 645, a second pulley 649 pivoted to the tiller 611a, and two third pulleys 649a symmetrically pivoted to the central body 611 and configured to deflect the loading thread 647 from a respective primary lever 614 and 615 towards the thrust accumulator 619 mounted on the tiller 611a.

In particular, in the present embodiment example of an archery tool 610 configured as a crossbow, the loading thread 647 comprises a first section 647a for the connection with the stem 645, and two second sections 647b for the connection with the respective primary levers 614 and 615.

The first section 647a and the second sections 647b are connected in such a way that the traction of a second section 647b is transmitted directly to the first section 647a.

In particular, the second sections 647b are part of a single thread connected to the first section 647a by means of an eyelet 647c , which eyelet 647c is crossed by the thread of the second sections 647b.

In particular, the first section 647a of the loading thread 647 is fixed at a first end to a fixed pin 650 integral with the tiller 611a, while it features the eyelet 647c at the second end.

Each of the second sections 647b is constrained at a first end to a corresponding pin 651, in turn fixed to a corresponding primary lever 614 or 615, and the other second section 647b is connected to the second end.

In particular, as already described above, the two second sections 647b are part of a single thread connected at its ends to the opposite pins 651 of the primary levers 614 and 615.

Said embodiment for the archery tool 610 configured as a crossbow is obviously to be understood as a non-limiting example of the invention.

For example, in a not shown variant embodiment, the two second sections 647b of the loading thread 647 are connected to the first section 647a by means of an intermediate slider block to which the corresponding ends of all said first section 647a and second sections 647b are constrained.

The thrust accumulator 619 is intended as to be installable both in such a way that, when the nocking string 612 is pulled, the springs of the thrust accumulator 619 are compressed in the direction going from the tiller 611a towards the central body 611, as shown in the FIGS. 40, 41, 41A and 41 B, and in such a way that the springs of the thrust accumulator 619 are compressed in the direction going from the central body 611 to the tiller 611a.

In both cases, it is possible to install a load increase device 261 as described above on the tiller 611a or a pre-loadable external auxiliary accumulator 361 as described above.

It has in practice been established that the invention achieves the intended task and objects.

In particular, with the invention a bow-type throwing tool has been developed which is simpler and faster to calibrate and adjust with respect to the bows of the known type.

Again in particular, with the present invention a bow-type throwing tool has been developed which has the capability of transmitting to an arrow a much higher amount of energy than known devices already on the market.

Furthermore, with the invention a throwing tool has been developed with which a better let-off is achieved with respect to the bows of the known type.

In addition, a bow-type throwing tool which is structurally simpler and easier to use has been developed with the invention.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; moreover, all the details may be replaced by other technically equivalent elements.

In practice, the materials used could be of any type, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, according to requirements and the state of the art.

If the characteristics and techniques mentioned in any claim are followed by reference signs, these reference signs are to be intended for the sole purpose of increasing the intelligibility of the claims and, consequently, such reference signs have no limiting effect on the interpretation of each element identified by way of example from these reference signs.

Claims

1. A bow-type throwing tool, comprising a central body, a nocking string for an arrow, and elastic energy storage means operated by the traction of said string,

said elastic energy storage means comprising: two opposed primary levers connected with hinging means to said central body, said nocking string being constrained by its opposite ends to opposite free ends of said primary levers; two opposed axial action thrust accumulators, defined on said central body; loading means of said axial action thrust accumulators configured to induce a compression in said thrust accumulators following a traction of said nocking string,

wherein said axial action thrust accumulator comprises at one end a fixed head and at the opposite end a movable head, said axial action thrust accumulator comprising a stem, translatable in the direction of its own axis, to which said movable head is constrained,

said loading means comprising, for each thrust accumulator: a loading thread, which is fixed at a first end to the central body and at the opposite second end to a corresponding primary lever; a pulley system configured to cause a translation of said stem, along the line of said axis and in the compression direction of a corresponding thrust accumulator, following a traction of said loading thread.

2. The throwing tool according to claim 1, wherein said hinging means comprise for each primary lever a pin, a notch being made on said pin for the passage of said loading thread, said notch being configured to allow the progressive reduction of the distance between the axis of the loading thread and the rotation axis of said pin during the traction step of the nocking string.

3. The throwing tool according to claim 1, wherein the distance of the axis of the loading thread from the rotation axis of the pin is near zero, remaining greater than zero.

4. The throwing tool according to claim 1, wherein said pin, at said notch, has a solid part configured to define a curved surface for the rest of said loading thread, said curved surface having a cusp, the distance between said cusp and the rotation axis of said pin being less than the radius of said loading thread.

5. The throwing tool according claim 1, wherein said central body comprises hinging appendages.

6. The throwing tool according to claim 1, wherein each primary lever comprises a free end and an opposite pivoting portion.

7. The throwing tool according to claim 1, wherein said central body comprises two opposite frames each defining a window, inside each of which windows there is a corresponding thrust accumulator.

8. The throwing tool according to claim 1, wherein each of said axial action thrust accumulators comprises at least one compression load spring, said axial action thrust accumulator comprising, in particular, a plurality of Belleville springs, arranged in series with each other.

9. The throwing tool according to claim 1, wherein said thrust accumulator comprises a stroke adjustment system, configured to limit the crushing of one or more springs.

10. The throwing tool according to claim 1, wherein said stem has a manoeuvring end, available for the connection with the loading means.

11. The throwing tool according to claim 1, comprises a pair of load increase devices, configured to operate in series with a corresponding thrust accumulator.

12. The throwing tool according claim 1, wherein said load increase device comprises:

a stem of the thrust accumulator, which is equipped with a striker head;

a containment box, fixed externally to the end of the frame;

a slider body placed so as to translate, along the thrust axis of the corresponding thrust accumulator, into a through hole defined at the end of the frame and into a coaxial guide hole defined in the containment box;

a plurality of thrust increase springs, placed so as to act between a cover of the containment box and a shoulder of the slider body;

an abutment element, configured to abut against the striker head of the stem, said abutment element being configured to be able to adjust its own axial position with respect to the slider body itself.

13. The throwing tool according to claim 1, comprises a pair of pre-loadable external auxiliary accumulators configured to operate in series with a corresponding thrust accumulator.

14. The throwing tool according to claim 1, comprising:

a stem of a corresponding thrust accumulator, which is equipped with a striker head;

a containment box, fixed externally to the end of the frame;

a first slider body placed so as to translate, along the thrust axis of the corresponding thrust accumulator, into a through hole defined at the end of the frame);

a second slider body placed so as to translate, along the thrust axis, into a guide hole defined on the first slider body and into a coaxial guide hole defined in the containment box;

a plurality of thrust increase springs, placed so as to act between a cover of the containment box and a first shoulder of the second slider body;

one or more accompanying springs, placed so as to act between the shoulder of the second slider body and a facing second shoulder of the first slider body;

a pre-load lever, pivoted to a bracket developing from the cover through a pin;

a pre-load tie rod connected at a first end to a first traction pin fixed to the second slider, and at the opposite second end to a second traction pin fixed to the pre-load lever;

an elastic return element constrained on one side to the cover and on the opposite side to the pre-load lever.

15. The bow-type throwing tool configured as a crossbow, characterized in that it comprisescomprising a central body from which a tiller, a nocking string for a dart and elastic energy storage means operated by the traction of the string develop, said elastic energy storage means comprising:

two opposed primary levers connected with respective hinging means to said central body, said nocking string being constrained by its opposite ends to opposite free ends of said primary levers

an axial action thrust accumulator, defined on said tiller;

loading means of said axial action thrust accumulator, said loading means being configured to induce a compression in the thrust accumulator following a traction of said nocking string.

16. A bow-type throwing tool, comprising a central body, a nocking string for an arrow, and elastic energy storage means operated by the traction of said string,

said elastic energy storage means comprising: two opposed primary levers connected with hinging means to said central body, said nocking string being constrained by its opposite ends to opposite free ends of said primary levers; two opposed axial action thrust accumulators, defined on said central body; loading means of said axial action thrust accumulators configured to induce a compression in said thrust accumulators following a traction of said nocking string.

17. Hinging means for a bow-type throwing tool, said bow-type throwing tool comprising a central body, a nocking string for an arrow, and elastic energy storage means operated by the traction of said string, said elastic energy storage means comprising two opposed primary levers connected with said hinging means to said central body, said hinging means comprising, for each primary lever, a pin, a notch being made on said pin for the passage of a loading thread, said notch being configured to allow the progressive reduction of the distance between the axis of said loading thread and the rotation axis of said pin during the traction step of the nocking string.

18. The hinging means according claim 17, wherein the distance of the axis of the loading thread from the rotation axis of the pin is near zero, remaining greater than zero.

19. The hinging means according to claim 17, wherein the distance between the cusp and the rotation axis of the pin is less than the radius of the loading thread.

20. The hinging means according to claim 17, wherein said notch is shaped in such a way that the axis of the loading thread stops at a distance from the axis of the pin which can be comprised between 1 and 5 hundredths of a millimeter, wherein

said distance between the axis of the pin and the axis of the loading thread corresponds to the difference between the radius of the loading thread and the distance between the cusp and the axis of the pin.

21. A pin for bow-type throwing tools, wherein a notch is made on said pin for the passage of a loading thread, said notch being configured to allow the progressive reduction of a distance between an axis of said loading thread and a rotation axis of said pin.

22. The pin according to claim 21, wherein at the notch, it has a solid part configured to define a curved surface for the rest of the loading thread.

23. The pin according to claim 21, wherein the notch is concave and the solid part of the pin is correspondingly convex.

24. The pin according to claim 22, wherein the curved surface has a cusp.

25. The pin according to claim 22, wherein the axis of the pin crosses the pin at the notch, and not at the solid part.

26. The pin according to claim 21, wherein said notch develops like an arc of a circle over an angle comprised between 180° and 200°.

27. A load increase devices, configured to operate in series with a corresponding thrust accumulator, said load increase device comprising:

a stem of the thrust accumulator, which is equipped with a striker head,

a containment box, fixed externally to the end of a frame,

a slider body placed so as to translate, along the thrust axis of the corresponding thrust accumulator, into a through hole defined at the end of the frame and into a coaxial guide hole defined in the containment box,

a plurality of thrust increase springs, placed so as to act between a cover of the containment box and a shoulder of the slider body.

28. The load increase devices according to claim 27, wherein said slider body also comprises an abutment element, configured to abut against the striker head of the stem, said abutment element being configured to be able to adjust the axial position with respect to the slider body itself, with the aim of defining the distance with the striker head.

29. A pre-loadable external auxiliary accumulator comprising:

a stem of a thrust accumulator which is equipped with a striker head;

a containment box, fixed externally to the end of a frame;

a first slider body placed so as to translate, along a thrust axis of the corresponding thrust accumulator, into a through hole defined at the end of the frame;

a second slider body placed so as to translate, along the thrust axis, into a guide hole defined on the first slider body and into a coaxial guide hole defined in the containment box;

a plurality of thrust increase springs, placed so as to act between a cover of the containment box and a first shoulder of the second slider body;

a pre-load lever, pivoted to a bracket, developing from the cover, through a pin;

a pre-load tie rod constrained at a first end to a first traction pin fixed to the second slider, and at the opposite second end to a second traction pin fixed to the pre-load lever;

an elastic return element constrained on one side to the cover and on the opposite side to the pre-load lever.

30. The pre-loadable external auxiliary accumulator according to claim 29, further comprising:

one or more accompanying springs, placed so as to act between the first shoulder of the second slider body and a facing second shoulder of the first slider body;

a stroke adjustment system for said accompanying springs, defined below by way of example by the striker perimeter wall.