Heavy machine guns, automatic grenade launchers, and similar heavy weapons are typically mounted on gun mounts that are fixed to a pedestal. These gun mounts and pedestals help support the weight of the heavy weapon while also allowing it to be pivoted around at various angles to aim.
One popular, standardized gun mount is the MK93 which can be used with heavy machine guns (e.g., M2HB/M3 0.50 Cal) or automatic grenade launchers (e.g., MK19 MOD 3 40 mm Automatic Grenade Launcher). MK93 mounts are typically used in conjunction with a Universal Pintle Adapter, Traverse and Elevation Mechanism, and Bearing Sleeve, which attaches to the socket on the vehicle turret A-Frame or tripod. MK93 mounts can be seen in several different patent publications, such as U.S. Pat. Nos. 8,578,644; 7,770,505; 8,584,393; and US 2016/0216056, all of which are hereby incorporated by reference.
Some MK93 gun mounts include recoil buffers which help absorb and reduce the force of kickback or recoil from each shot fired from the gun. In this respect, the recoil buffers can significantly improve aim and control of the gun, and therefore shot grouping. Highly reproducible buffering and elimination of variation of the buffering performance is thought to reduce or limit negative recoil influences on the accuracy of the shots fired from the gun.
Therefore, a MK93 buffer that provided more reproducible buffering and reduced buffer variations would be valuable for improving the accuracy and shot grouping of machine guns.
The present invention is generally directed to a recoil buffer or piston that can be used in gun mounts such as the MK93 mount. In one embodiment, the recoil buffer can complete a displacement cycle (i.e., depressing the piston shaft and returning it to the original uncompressed position) in less than 0.1 second. In another embodiment, the recoil buffer can complete a displacement cycle in about 0.06 seconds.
In one embodiment, the recoil buffer includes an inner spring and an outer spring that are positioned against a piston within the recoil buffer housing. The piston also includes multiple ball valves (e.g., 3) that are configured to close off passages through the piston during the compression portion of the displacement cycle and to open during the decompression portion of the displacement cycle.
In another embodiment, the recoil buffer has a single spring positioned against a piston within the recoil buffer housing to as to bias the piston to a decompressed position. A shim valve closes off passages through the piston during the compression portion of the displacement cycle and opens up the passages during the decompression portion of the displacement cycle. The shim valve is formed by a plate member that axially slides on a post on the piston. Optionally, the piston may include several raised features that engage or mate with grooves in the plate member so as to ensure even movement of the plate during a displacement cycle. These features also help prevent the spring from interfering with the plate.
These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which
Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In that respect, elements and functionality of one embodiment not necessarily only limited to that embodiment and may be combined with other embodiments shown herein in any manner that would result in a functional embodiment. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements, including between different embodiments.
As discussed in greater detail below, one embodiment of the present invention is directed to a buffer or piston for an MK93 gun mount in which the piston shaft returns to an uncompressed position in a shorter time (e.g., 0.06 seconds or less) and with greater regularity than current prior art designs. The time the piston shaft completes its displacement cycle and returns to its uncompressed position is an important buffer characteristic. For a single shot, the return time may be of lesser importance, but when multiple shots are fired quickly, as a machine gun is capable of, the slow return time can result in increasing displacement of the piston shaft and possibly reduced firing rate until the buffer is no longer able to mitigate the recoil energy of the gun. In other words, if the buffer does not complete its displacement cycle quickly enough, each shot will start the displacement cycle at an increasingly compressed position until the piston shaft can no longer be compressed.
Once the piston shaft 24 has been displaced from the recoil force, the spring 30 pushes the piston 26 outward of the compression chamber (i.e., to the left of the figure). The ball member 28A then moves away from the passage 28B, opening up the valve 28 and allowing hydraulic oil out of the compression chamber. Additionally, the bleed passages 27 allow for the hydraulic oil to slowly flow through during compression.
In operation, when the gun attached to the MK93 gun mount 10 is fired, the recoil force causes the piston shaft 104 to be quickly pushed into the housing 102. As discussed further below, the components within the buffer 100 then push the piston shaft 104 back out of the housing 102 to its starting position.
Turning first to the outer spring 110, in one embodiment this spring 110 is disposed on a ledge 106A of the piston 106 (see
The inner spring 112, is disposed against the inner raised surface of the piston 106 (see
The three ball valves are located at equal distances from each other in the radial dimension. As seen best in
Turning first to the spring 210, it preferably has an outer diameter of about 0.875 inch, a wire diameter of about 0.120 inch, an uncompressed length of about 2.25 inches, and a spring rate of about 78.65 lb/inch. The spring 210 preferably contacts a side surface of the piston 206 and a side of the compression chamber 202A opposite the piston 206.
The shim valve 205 is composed of a plate 212 (see best in
As seen best in
The plate 212 can take the form of a variety of shapes, such as a circular or square shaped plate. In the present embodiment, the plate 212 has a cross shape with large grooves that are shaped to mate with raised structures 206A on the piston 206A. The raised structures 206A help ensure that the plate 212 moves evenly relative to the piston 206. In one example, the plate 212 has a diameter of about 0.810 inches, an inner aperture diameter of about 0.229 inches, and a diameter between the grooves of about 0.430 inches.
The embodiments of this application may use a hydraulic fluid with a viscosity of preferably 50 cs that demonstrates both high and low temperature stability. For example, Dow Corning 510 phenylmethyl polysiloxane may be used.
The housing of the embodiments of the present invention can be composed of steel or anodized aluminum. The anodized aluminum may be preferable because this material provides better temperature dissipation which can otherwise destroy seals and lead to irregular buffer behavior.
Test Results
The current landscape of recoil buffers for heavy machine guns was found to be made up of products by companies such as Enidine, Taylor, Kynshot, and Ringfeder. The respective buffers were obtained and tested for a purpose built MK93 Recoil Simulator which used a motor and rotating wheel to move a mass of about 42 lbs against a tested buffer. The time to return of the shaft to uncompressed position and maximum displacement were measured on the different buffers, as well as the temperature to determine the developed heat during dynamic cycling.
Several of the buffers did not return within a desired amount of time (more than 0.1s based on a maximum firing rate of 600 rpm), thus leading to increasing displacement throughout dynamic testing at 550 rpm until the maximum displacement of about 1 in (defined by the spring reaching solid state, thus maximum displacement of the shaft and piston) is reached and the buffer no longer mitigates recoil energy.
Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.
This application claims priority to U.S. Provisional Application Ser. No. 62/807,678 filed Feb. 19, 2019 entitled Recoil Buffer, which is hereby incorporated herein by reference in its entirety.
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Number | Date | Country | |
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20200263949 A1 | Aug 2020 | US |
Number | Date | Country | |
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62807678 | Feb 2019 | US |