Patent Grant
7121032
This invention relates to the field of firearms, and more particularly to an improved recoil force reduction apparatus for a shoulder firearm, such as a rifle or shotgun, the apparatus including a combination of hydraulic and elastomeric features.
It is commonly well known that shoulder firearms, such as rifles and shotguns, recoil suddenly and violently in a rearward direction when the firearm is discharged. The amount of resulting force that is felt by the shooter is jarring and is often uncomfortable, and to that end there have been numerous attempts that have been made in the field to devise a recoil reducing apparatus in an effort to dissipate the recoil force, rather than to have the shooter receive a sharp blow to the shoulder.
The types of recoil reducing apparatus that are presently known have included numerous mechanical and/or pneumatic systems and hydraulic type devices. For example, Ahearn, U.S. Pat. No. 3,233,354, relates to a class of hydraulic-type recoil reducing apparatus. According to the Ahearn patent, a recoil apparatus interconnects the butt portion (the portion of the stock which engages the shoulder of the shooter) and the forepiece of the stock. This apparatus includes a hydraulic cylinder and piston which axially reciprocates so as to permit hydraulic fluid contained in the cylinder to escape about the piston in order to permit relative movement between the two portions of the stock in a controlled manner and in which the recoil force is absorbed by the motion of the piston through the fluid.
A fundamental problem found in hydraulic type recoil reducing apparatus, such as described by Ahearn, is their insensitivity to certain factors, such as the type of ammunition used and the weight of the firearm itself. For example, a selection of different types of ammunition will often be commercially available for a particular caliber or gauge of the firearm, meaning that the shooter is free to select the ammunition most suited to his or her application. In addition, the shooter may select a particular type of ammunition in order to obtain particular ballistics or firing characteristics. Each of the preceding factors contribute to the recoil characteristics of the firearm and therefore may limit the effectiveness of the recoil reducer apparatus.
Therefore, attempts have been made in an effort to provide adjustability in such apparatus. U.S. Pat. No. 4,439,943 to Brakhage is an example of a recoil reducer apparatus that provides adjustability. In brief, this rather complex apparatus includes a pair of pistons, namely a primary piston and a secondary piston, which are provided within a hydraulic cylinder. A piston rod extends through the secondary piston and partially into the main piston through an aperture. The aperture according to this disclosure is frusto-conical to permit the attachment of a frusto-conical piston rod end. The pistons are supported to prevent rotation and a passage is formed between the frusto-conical portion of the aperture and one side of the main piston to permit fluid to pass therethrough during recoil. The secondary piston which is sealed to prevent fluid leakage provides a biasing force to return the apparatus (i.e., the main piston) to a neutral position. Turning of the piston rod changes the characteristics of the passage and therefore changes the damping characteristics of the apparatus as fluid passes through the piston when the firearm is discharged.
Other forms of recoil reducing apparatus include pads that are added to the shoulder firearm, the pads being at least partially defined by an elastomeric material. These devices, however, are able to provide only a fractional amount of energy absorption and are therefore only moderately effective.
It is therefore a primary object of the present invention to improve upon the above-noted deficiencies of the prior art.
It is another primary object of the present invention to provide a recoil pad that can be integrally or otherwise mounted to the stock of a rifle or other shoulder firearm that will provide energy absorption when the rifle is fired in order to reduce the impact or recoil force that is felt by the shooter.
It is yet another primary object of the present invention to provide a recoil pad in a manner that is relatively easy to manufacture and at a substantially lower cost than currently known devices of this type.
It is yet another primary object of the present invention to provide a recoil pad device that provides improved performance for a given pad deflection, as compared to other recoil pad devices.
It is still another primary object of the present invention to provide a recoil pad design that provides improved performance over a wide and diverse range of ammunitions.
Therefore and according to a preferred aspect of the present invention, there is provided a recoil pad for a shoulder firearm, said recoil pad being mounted to or integrated within the stock of a shoulder firearm. The recoil pad includes at least one internal cavity or chamber having a quantity of fluid contained therein and a piston assembly. Discharge of said firearm causes hydraulic orificing of the fluid through a fixed or variable orifice area caused by movement of the piston assembly through the chamber. This hydraulic orificing generates a force in the recoil pad and absorbs energy by transferring the energy into heat that is dissipated into the environment, rather than storing the energy and releasing same back into the firearm.
According to one version, the movement of the piston through the confines of a hydraulic fluid column causes a reduction in the volume retaining the hydraulic fluid and thus orificing of the fluid around the piston which produces a damping effect. Moreover and according to this version, a portion of the volume of hydraulic fluid contained within a first interior chamber into which the piston is moved is caused to be displaced from the first interior chamber to a second adjacent accumulator chamber. The accumulator chamber is sealed to the remainder of the recoil pad apparatus with the exception of the first chamber and already includes therein a quantity of air. The introduction of hydraulic fluid from the first chamber coupled with the movement of the piston assembly causes the air within the accumulator chamber to compress. According to another version, the recoil pad comprises a piston assembly including a piston head and a pair of piston rods extending therethrough. According to this version, the recoil force causes the piston head to be moved through a fluid column wherein the hydraulic orificing occurs either through or around the piston head.
According to the invention, the recoil pad combines at least one hydraulic element, such as the above noted piston, as well as at least one elastomeric element in order to effectively absorb the recoil energy associated with the firing of a shoulder firearm, such as a rifle. As noted, the hydraulic element preferably includes a hydraulic fluid into which the piston is brought in contact. As the firearm discharges, the hydraulic fluid is pressurized within the confines of the pad and hydraulic fluid is orificed around or through the piston head, thereby creating a resisting force.
In addition, the at least one elastomeric element of the herein described recoil pad absorbs a small portion of the energy and creates a preload force to insure the recoil pad will not stroke until a predetermined force is exceeded. Moreover, the elastomeric element also provides the biasing force required to return the recoil pad for the next firing of the firearm after the energy absorption cycle has been completed. The recoil pad can also include, for example, a coil spring or other means to provide the necessary return force, such as that produced by a compressed volume of air in an adjacent accumulator chamber by the piston.
An advantage provided by the present invention is that the design of the above described recoil pad, through the hydraulic orificing of fluids, can be used with a wide range of ammunitions, thereby producing a velocity sensitive damping force. The stock can be modified to contain the recoil pad within the stock of the firearm or can be separately mounted as an accessory component.
Another advantage of the present invention is that through hydraulic orificing of fluid and by varying the orifice area versus the deflection of the recoil pad an improved performance for a given pad deflection is provided, as compared to prior art recoil pad devices.
Another advantage of the present invention is the ease of manufacture due to the reduced number of components required, and therefore the herein described apparatus can be manufactured and sold at lower cost.
These and other objects, features and advantages of the present invention will become readily apparent from the following Detailed Description that should be read in conjunction with the accompanying drawings.
The following description relates to a hydraulastic recoil pad for a shoulder firearm, Such as a rifle or shotgun in accordance with a number of embodiments. It should be readily apparent, however, that the herein described recoil pad can be similarly used with other commercially available shoulder firearms, other than specifically described herein. In addition and throughout the description which follows, several terms are used in order to provide a suitable frame of reference with regard to the accompanying drawings, such as “front”, “back”, “top”, “bottom”, and the like. These terms, however, are not intended to be over limiting or to restrict the scope of the invention in accordance with the present claims, except where specifically indicated.
The term “hydraulastic” as used herein refers to a combination of hydraulic and elastomeric features that are present in the recoil pad in accordance with the present invention. The term “proximal” as used herein for purposes of this discussion refers to the side of the recoil pad apparatus or direction that is in relation closer to the shoulder of the shooter and the term “distal” as used herein for purposes of this discussion refers to the side of the recoil pad apparatus or direction that is in relation closer to the rifle or shoulder firearm.
Referring to
The chamber assembly 53 is preferably a plastic molded unitary component, including a pair of adjacent chambers, namely a first chamber 57 and an adjacent second chamber 59. Each of the first and second chambers 57, 59 are defined by side walls 51 defining each respective chamber, as well as a single open end 61, 62, each open end facing the distal side of the recoil pad 40. A piston assembly 63 is sized to be fitted onto the interior cavity of the elastomeric pad enclosure 56 at the distal side of the recoil pad 40 and in particular is fitted to cover the open ends 61, 62 of the first and second adjacent chambers 57, 59. The piston assembly 63 includes a base portion 65 supporting a center piston portion 67. The base portion 65 is defined by a plate-like planar portion which is fitted in the distal end of the elastomeric pad enclosure 56 and includes a pair of openings 47 that permit the recoil pad 40 to be assembled to the stock of a rifle by means of fasteners (not shown). The center piston portion 67 is a distal extension of the base portion 65 that includes a housing 69 having disposed therein a cylindrical or round piston head 66, as well as an adjacent interior cavity 71 defined by the exterior wall of the piston head and the interior wall of the housing 69 that covers the second chamber 59 wherein the confines of the second chamber and the interior cavity of the piston assembly combine to form an accumulator chamber. A quantity of a hydraulic fluid 79, such as silicone fluid, is added within the confines of the first chamber 57 to a predetermined level therein, the level being variable, the fluid being added by means of a fill port 70 which is provided on the exterior of the distal facing side of the center piston portion 67 of the piston assembly 63 and extending into the interior cavity 71 thereof and is sealed with a fill plug.
A spacing or gap 75 is provided between the proximal facing surface 85 of the base portion 65 and the distal facing surface 81 of the elastomeric pad enclosure 56 wherein interior walls of the base portion effectively covers the side walls 51 of the adjacent first and second chambers, 57, 59 respectively. An annular O-ring 77 or similar seal is further provided therebetween to provide an effective fluid-tight seal between the exterior of the fitted chamber assembly 53 and an interior surface of the base portion 65, the interior surface including an annular groove retaining the O-ring 77. The spacing 75 permits compression of the elastomeric pad enclosure 56 with the action of a recoil force, as described below.
Finally, a pair of access openings 49 extend through the proximal side of the elastomeric pad 56 and are axially aligned with the openings 47 provided in the base portion 65, thereby permitting adjustment/replacement of the recoil pad 40, as needed.
In operation, a recoil force supplied by the action of firing the rifle (not shown) causes the stock to move in a rearward direction (i.e., proximally) toward the shoulder of the shooter. This movement causes the attached base portion 65 of the recoil pad 40 to also be shifted in a rearward direction, due to the attachment of the base portion by fasteners (not shown) through openings 47 extending to the rifle stock. Similarly, the remainder of the piston assembly 63, including the center piston portion 67, is also caused to similarly translate towards the fixed position of the fitted chamber assembly 53 containing the two chambers 57, 59 attached to the interior surface of the elastomeric pad 56.
As a result of this latter movement, the elastomeric pad 56 is compressed with the piston head 66 being caused to move into the cavity of the first chamber 57. The volume of the first chamber 57 is therefore reduced and as a result hydraulic fluid 79 initially contained within the first chamber 57 is pressurized and displaced from the first chamber about the periphery of the piston head 66 to the adjacent accumulator chamber 59, 71 due to the relative movement between the piston head 66 and the recoil pad. As the piston head 66 is shifted laterally, the orifice area (that is, the area formed by the gap between the outside of the piston head 66 and the inside walls of the first chamber 57) can be decreased by tapering the outside of the piston head and therefore more force is required in order to move the hydraulic fluid 79. As a result, energy is absorbed by the hydraulic fluid 79 and transferred into heat rather than transferring the energy back into the firearm. The air in the adjacent accumulator column provides a restoring force in that the air is compressed in the accumulator chamber 59, 71 and is sealed to prevent fluid leakage, other than with the adjacent first chamber 57. Upon cessation of the recoil force, the force of the compressed air causes any displaced hydraulic fluid to be pushed back (i.e., distally) about the piston head 66 and into the confines of the first chamber 57 and further causes the piston assembly 63 to assume its initial position. The elastomeric pad 56 also assists in providing a repeatable restoring force for the recoil pad 40.
It should be readily apparent that alternative designs that embody the above concepts are possible to those of sufficient skill in the field. For example, a second alternative embodiment to the recoil pad shown above is depicted in
Like the preceding design, the recoil pad 90 is defined by three (3) primary components; namely, a piston assembly 98, a fitted chamber assembly 100 and an elastomeric pad enclosure 102. The primary difference between the instant design and the design of the first embodiment is that the base portion 104 of the piston assembly 98 according to this embodiment extends coplanarly with the center piston portion 109 so that the recoil pad can be mounted directly to the end of the firearm stock, rather than integral thereto. Otherwise, the instant design performs in the same manner functionally wherein the piston assembly 98 includes a cylindrical or other suitably shaped piston head 106 which is placed initially into contact with the elastomeric pad 102, the piston being arranged in relation to a first interior chamber 110 that is at least partially filled with a hydraulic fluid 114, such as silicone fluid. As in the preceding embodiment, the first interior chamber 110 is filled to a predetermined level using a fill port 120 attached to the distal facing side of the piston assembly 98, permitting fluid movement when the cylindrical piston head 106 is moved therethrough.
As the entirety of the piston assembly 98, and more particularly the piston head 106, translates axially toward the proximal end of the apparatus 90 under the action of the recoil force of the firearm, the volume of the first chamber 110 is effectively reduced and the hydraulic fluid 114 contained in the first chamber 110 is pressurized by the proximal facing surface 107 of the piston head 106. As a result of this rearward movement and the noted fluid compression, a portion of the hydraulic fluid 114 in the first chamber 110 is caused to move around the entering piston head 106 into the adjacent accumulator chamber 118 formed between the exterior wall of the piston head 106 and the interior wall of the accumulator chamber. In the meantime, the variability of the orifice area formed by the gap created by the outside of the piston head 66 and the inside walls of the first interior chamber 110 produces damping based on the compressed hydraulic fluid 114 within the shrinking first chamber 110, effectively reducing the shock load provided against the shoulder of the shooter, the energy being dissipated into the fluid as heat which is then conducted into the environment.
The accumulator chamber is essentially formed from the interior of the second adjacent chamber 118 as well as that of the interior cavity 117 adjacent to the piston head 106 of the piston assembly 98. The volume of air that is retained within the accumulator chamber 117, 118 is also compressed due to the influx of hydraulic fluid 114 passing therein as well as the relative rearward movement of the recoil pad against the elastomeric pad 102, as braced by the shoulder of the shooter. The result is an elastomeric biasing force that biases the piston assembly 98 to return the piston assembly 98 to a neutral position upon cessation of the recoil force. This elastomeric biasing force further is sufficient to return the hydraulic fluid 114 back into the first interior chamber 110. The assembly 90 then assumes the initial or original prefired position shown in
Referring to
A piston assembly 188 comprises a piston head 192, which according to this embodiment, is a disc-like member made from a suitable moldable plastic material, that is fitted within the formed interior cavity 168 of the body portion 164. Alternatively, however, other suitable lightweight materials can be used. The piston head 192 includes a pair of spaced through openings 196, 200 which are axially aligned with the above-noted openings 180 formed in the distal end wall 172 of the body portion 164. The above openings 180, 196, and 200 are sized to receive a corresponding pair of axial piston rods 206, the rods being preferably substantially round in cross-section. The piston rods 206 each extend in a parallel spaced relationship through the entirety of the body portion 164 of the herein described apparatus 160. A cylindrical bearing block 210 is fixedly attached to the open proximal end of the body portion 164, the bearing block being mounted adjacent to the piston head 192 and including an annular shoulder 214 which is received within a recess 218 formed in the proximal end of the body portion 164 in which the block is fixedly mounted. The bearing block 210 includes a pair of spaced openings 211 extending through the block that are sized to receive the axial piston rods that extend therethrough, the block further including flanges 217 extending from a proximal end thereof through which the rods further extend rearwardly. The bearing block 210 is also preferably formed from a suitable plastic, or other lightweight materials could easily be utilized.
The bearing block 210 is defined with an O-ring 222, which is provided in an annular groove 226 along an outer peripheral portion thereof, the O-ring engaging with the interior surface wall of the body portion 164 in order to form a fluid-tight seal. Likewise, the piston head 192 similarly includes an O-ring 230 that is provided in an annular groove 234 on the outer periphery thereof, the O-ring also engaging the interior wall surface of the interior cavity 168 of the body portion 164 in order to provide an effective fluid-tight seal therewith. If an annular orifice is used, the O-ring 230 and the annular groove 234 are removed and fluid is permitted to flow about the piston head 192. Alternatively, an orifice opening 285 or openings in the piston head 192 can be employed to orifice hydraulic fluid from one side of the piston head 192 to the other side thereof.
The axial piston rods 206 each extend proximally from the openings 211 formed in the bearing block 210 and outwardly from the flanges 217 extending from the proximal end thereof, the proximal ends of the piston rods being seated into a pair of receiving mounts 250 that are formed on the distal side of a plate member 248. The plate member 248 is spaced a predetermined distance from the proximal end wall of the body portion 164, as shown more clearly in
A pair of coil springs 272 are attached in overlaying relation relative to the predetermined spaced area 276 that is defined between the plate member 248 and the body portion 164, each coil spring being mounted onto a corresponding piston rod 206 and secured at either end to the exterior of the receiving mounts 250 and the flanges 217. The recoil pad 160 is shown in an initial position in
An elastomeric pad covering 224, made from an elastomeric material, is provided that covers the proximal end of the body portion 164 as well as the plate member 248 and the predetermined spaced area 276. Preferably, the elastomeric pad covering 224 is reinforced and shaped along the proximal end thereof so as to contour to the shoulder of the shooter, as shown most clearly in
The recoil pad 160, according to this embodiment, is attached to the butt end of a rifle stock (not shown) through a pair of spaced openings 245 that are provided in a proximal end wall 189 of the body portion 164, the end wall being disposed radially outboard of the seated bearing block 210. Access holes 249 are further provided in the plate member 248 that are axially aligned with the openings 245 to permit access to fasteners (not shown) securing same so as to permit removal/replacement, as needed.
The interior cavity 168 formed by the body portion 164 between the distal side of the piston head 192 and the interior distal end wall 172 of the body portion 164 is sized to define a fluid chamber which is initially filled to a predetermined level with a hydraulic fluid, such as silicone fluid, (not shown) by means of a fill port (not shown). The fill port and fill plug can be sealingly provided in the bearing block 210 or can otherwise be provided.
As noted, the axial piston rods 206 are substantially cylindrical and include a common cross section with the exception of the annular grooves formed to receive the above-noted O-ring seals. In addition, an axial portion 209 of each piston rod extending through the piston head 192 is made with a smaller or narrowed diameter than the remainder of the piston rod 206. The design shown incorporates a piston head 192 that is molded around the piston rods 206. The smaller diameter on the piston rods 206 provides a bearing area to transfer load from the piston head 192 to the piston rods 206. Other types of connections between the piston head 192 and the piston rods 206, such as a threaded connection, can also be employed without deviating from the intended scope of the invention.
Still referring to
In the meantime, the initial biasing force of the coil springs 272 that are fixedly secured to the plate member 248 provide a centered restoring force in order to cause the body portion 164 to be shifted back to the initial position of
It should be realized that the particular recoil pad design can be modified to achieve the same function. For example, and rather than displacing hydraulic fluid through an orifice hole or opening 285 or openings, the O-rings located on the periphery of the piston head 192 could be removed in favor or providing the same orifice area as the orifice opening 285 in the piston head. As such hydraulic fluid would be then be directed around the periphery of the piston head 192, as the piston head translates axially through the chamber.
While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawings, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the claims.
Though the present invention has been described in terms of certain embodiments, it will be readily apparent to one of sufficient skill in the field that modifications and variations can be made using the inventive concepts described herein according to the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 837601 | Behr | Dec 1906 | A |
| 2344752 | Utz | Mar 1944 | A |
| 3001312 | Campbell | Sep 1961 | A |
| 3039222 | Hoge | Jun 1962 | A |
| 3176424 | Hoge | Apr 1965 | A |
| 3209482 | Kuzma et al. | Oct 1965 | A |
| 3233354 | Ahearn | Feb 1966 | A |
| 3371442 | Carlson | Mar 1968 | A |
| 3707797 | Ruth | Jan 1973 | A |
| 3714726 | Braun | Feb 1973 | A |
| 4439943 | Brakhage | Apr 1984 | A |
| 4663877 | Bragg | May 1987 | A |
| 5031348 | Carey | Jul 1991 | A |
| 20030154640 | Bragg | Aug 2003 | A1 |
| 20040031182 | Bentley | Feb 2004 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20060168869 A1 | Aug 2006 | US |
