BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic cross-sectional side view of one embodiment of the present invention.
FIG. 2 is a three dimensional illustration of the bolt, the integrally buffered spring and the extractor of one embodiment of the present invention.
FIG. 3 is a top view of the bolt illustrated in FIG. 2.
FIGS. 4A, 4B, 4C and 4D are different views of the extractor illustrated in FIG. 2.
FIG. 5 is a cross-sectional view of the bolt depicted in FIG. 2 in the direction of A.
FIG. 6A is an illustration of a spring according to one embodiment of the present invention.
FIG. 6B is a cross-sectional view of the bolt depicted in FIG. 2 showing a pair of tapered spring wells containing integrally dampened springs.
FIG. 7 is an end view of the bolt depicted in FIG. 2.
FIG. 8 is an end view of the barrel interface of the rifle depicted in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and language will be used to describe the same. It should be understood that no limitation of the scope of the invention is intended by the illustrations; alterations and further modifications of the illustrated device and such further applications of the principles of the invention as illustrated herein being contemplated and fully expected to fall within the scope of the invention.
A firearm according to one embodiment of the present invention is depicted in FIG. 1 and designated generally as 10. Firearm 10 has barrel 12 and magazine 14. Magazine 14 is configured, as is well-known in the art, to feed cartridges 52 to a cartridge chamber through cartridge chamber interface 18. The cartridge chamber is defined by receiver 20. Receiver 20 includes trigger assembly 22 with spring-loaded trigger 24, spring-loaded hammer 26, and firing pin 28. Receiver 20 also defines a cavity configured to house bolt carrier 32. Bolt carrier 32 includes a bolt 34 residing therein. Bolt 34 defines firing pin bore 36 for receiving firing pin 28 therethrough. Bolt 34 also includes a spring-loaded extractor 42 pivotably coupled thereto. Extractor 42 has guide flange and is pivotably coupled by pivot pin 48 to bolt 34. Barrel 12 is coupled to barrel extension 50. Barrel extension 50 defines a firing chamber therein for receiving a cartridge 52 chambered by bolt carrier 32.
Referring now to FIGS. 2, 3 and 5, further description of bolt 34, shown removed from bolt carrier 32, is provided. Bolt 34 defines an elongate body having a proximal end 54 and an opposite distal end 56 along longitudinal axis L. Bolt 34 includes integrally formed stem 58 adjacent proximal end 54. Circumferential flanges 60 are integrally formed with stem 58. The flanges 60 form a groove 62 therebetween for receiving a sealing ring (not shown). Bolt 34 is also formed with a neck portion 64 extending from the flanges 60 to cylindrical body portion 66. Cylindrical body portion 66 defines a first bore 68 and a second pin bore 70 therethrough. Cylindrical body portion 66 also defines an outer surface 72 thereabout and a cartridge bearing surface 74 at distal end 56.
The outer surface 72 of the bolt 34 has a lug bearing portion 76 adjacent distal end 56. Body portion 66 of bolt 34 also defines extractor recess 78. The extractor recess 78, formed on the outer surface 72, is in communication with firing pin bore 36 and is configured to receive extractor 42 therein. An extractor bearing portion 80 resides within extractor recess 78 adjacent distal end 56 and is integrally formed with body portion 66. Extractor bearing portion 80 is configured to engage an underside 82 of extractor 42. In a preferred embodiment, extractor bearing portion 80 includes a mating surface 84 (see FIG. 2) defining a curved plane substantially parallel to the outer surface 72 of the bolt 34 such that cartridge bearing face 74 is circular. The underside 82 of extractor 42 is also preferably curved so that it engages bearing portion 84 in a form fitting engagement. In another embodiment, underside 82 of extractor 42 and mating surface 84 define a substantially flat plane.
Referring now to FIGS. 2 and 4A-4C, extractor 42 includes a guide flange 44 at first portion 90, extractor flanges 92 at second portion 94, and an extractor body 96 extending therebetween. Extractor recess 78 is positioned on cylindrical body portion 66 such that first portion 90 of extractor 42 substantially coincides with distal end 56 of bolt 34. Lip 98 of extractor 42 is then biased between a first and second position to removably retain a cartridge (not shown) in cartridge recess 100 (see FIG. 5) formed at distal end 56. At the underside 82 of each of the flanges 92 of extractor 42 is a spring stabilizing pin or nipple 102 designed to engage an integrally dampened extractor spring 104.
Cartridge recess 100 includes cartridge bearing face 74. The retained cartridge resides within cartridge recess 100 such that the end of the cartridge bears against bearing face 74 to transfer the load from firing the cartridge to the bolt 34. Extractor mating surface 84 defines a portion of the circumference of cartridge bearing surface 74.
Preferably, the circumference of cartridge bearing surface 74, including the portion defined by mating surface 84, is circular and cartridge bearing surface 74 receives the entire circular end portion of the retained cartridge in bearing engagement. In another embodiment, mating surface 84 and underside 82 of extractor 42 define a flat plane, and the circular end of the retained cartridge is not fully received in bearing engagement against cartridge bearing surface 74. A portion of the end of the cartridge projects above mating surface 84. In the preferred embodiment, the co-extensive bearing surface reduces and more evenly distributes the stress on the bolt lugs created during firing and extraction of the cartridge. Extractor 42 also includes pin receiving portion 110 extending therefrom. Pin receiving portion 110 defines extractor bore 112 therethrough. Extractor bore 112 is configured to align with pin bores 70 when extractor 42 is positioned within extractor recess 78. Pivot pin 114 is extended through pin bores 70 and extractor bore 112 to pivotably engage extractor 42 to bolt 34.
Referring to FIG. 2 and FIG. 6B, extractor recess 78 is provided with a pair of spring wells 116. Spring wells 116 are formed in body portion 66 on opposite sides of firing pin bore 36. The central axes of the spring wells 116 are parallel to one another and are perpendicular to the longitudinal axis of the bolt. Spring wells 116 are each configured to receive an extractor spring 104 therein as more clearly illustrated in FIG. 2. The spring wells 116 are preferably tapered, and are sized and configured to receive a spring 104 that is preferably sized and configured with a slightly larger base coil 105 in order to minimize lateral movement of the spring 104 inside the well 116. (See FIGS. 6A and 6B). Referring to FIG. 6B, the larger base coil 105 allows the spring to be captured at the bottom of the spring well; the buffer dampens spring bounce; and the tapered spring well minimizes spring contact with the walls under distortion. In a preferred embodiment, the base coil is about 5% larger in diameter than the rest of the spring coils. When extractor 42 is engaged to bolt 34 as described above, each one of the nipples 102 on the flanges 92 engages a corresponding spring 104 positioned in a spring well 116. The preferred dimensions, in inches, of a spring and spring well according to one embodiment of the present invention are shown in FIG. 6B. The degree of taper of the spring well 116 is shown as an angle θ. Angle θ is preferably in the range from about 2 to about 6 degrees, more preferably, about 40. In a preferred embodiment, each spring 104 contains an integral buffer 120. The springs 104 are configured to pivotably bias extractor 42 radially inward to allow lip 98 to engage the rim of a cartridge. However, springs 104 must have the requisite flexibility to allow movement of extractor lip 98 radially outward to eject a cartridge.
The positioning of integrally dampened springs 104 inside the tapered spring wells 116 provides many advantages over prior art bolt designs. Lateral movement of the springs is decreased not only by the larger-base coil design of the springs 104 and the tapered spring wells 116, said lateral movement is further decreased by the engagement of the springs by the extractor nipples 102 on the underside 82 of the flanges 92 of extractor 42. Vibrational motion of the spring is further dampened by use of an integral buffer 120. The integral buffer 120 can be made with any material known in the art. The buffer material should be heat resistant to at least 500 degrees Fahrenheit; leaving no chance of burning from the heat generated by the rifle.
Referring now to FIG. 7, lug bearing portion 76 includes a number of bolt lugs 130a, 130b; 132a, 132b; 134a, 134b; and 136. To spread the recoil forces as evenly as possible, the bolt preferably has an odd number of lugs spaced, with the exception of the lugs adjacent to the extractor recess, equidistant apart. For example, the bolt depicted in FIG. 7 has seven lugs. Each bolt lug radially extends about the longitudinal axis of the bolt. Lugs 130a, 130b are collectively designated as lug pair 130 and extend opposite each other. Lugs 132a, 132b are designated as lug pair 132 and extend radially opposite each other. Finally, lug pairs 134a, 134b are designated as lug pair 134 and likewise extend radially opposite each other. Bolt lug 136 has no paired lug and extends radially opposite extractor 42, which is positioned between adjacent first lug 130a and second lug 134b.
Each adjacent pair of bolt lugs defines a gap 138 therebetween. The first lug 130a and the second lug 134b are adjacent to one another and define an extractor gap 140. Extractor gap 140 is configured to receive the first portion 90 of extractor 42. Each lug 130a, 132a, 134a, 136, 130b, 132b, and 134b defines a corresponding end face 142a, 142b, 142c, 142d, 142e, 142f and 142g (collectively designated as end face 142), respectively and a pair of sidewalls 144. In the prior art, first lug 130a and second lug 134b are most susceptible to failure because they are undercut by the extractor recess in order to accommodate the first portion 90 of the extractor 42. In a preferred embodiment of the present invention, first lug 130a and second lug 134b are not undercut by the extractor recesses as the mating surface 84 does not extend under the plain of the sidewall 144 of the first lug 130a and second lug 134b.
Receiver 20 also includes barrel extension 50 as illustrated in FIG. 1. Barrel extension 50 is configured to interlock with lug portion 76 of bolt assembly 32 during firing of the firearm. Barrel extension 50 includes a barrel receiving end opposite a bolt receiving end. Adjacent the barrel receiving end is a connecting portion which is configured to engage barrel 12 as is known in the art.
The bolt receiving end includes extension lugs 212. (See FIG. 8). Extension lugs 212 define receiving gaps 214 therebetween. Feed ramp 216 is defined proximate a pair of adjacent extension lugs 212 to facilitate insertion of a cartridge and lug portion 76 through bolt receiving end 204. Each extension lug 212 defines an interlock face which engages a corresponding one of the lug bearing faces of the bolt lugs.
In operation, bolt carrier 30 moves in a reciprocal fashion along longitudinal axis L when rounds are fired from firearm 10 in a conventional automatic or semi-automatic manner. This operation is well-known in the art. U.S. Pat. No. 2,951,424 to Stoner, U.S. Pat. No. 3,198,076 to Stoner, and U.S. Pat. No. 5,351,598 to Schuetz provide further information pertinent to this process and are incorporated herein in their entireties. Generally, the operation begins with a cartridge from magazine 14 being fed into cartridge recess while bolt 34 is in the open position, as shown in FIG. 1. Bolt 34 then slides forward in the direction indicated by arrow B to position the cartridge in firing chamber 16. As bolt 34 moves forward, the lug pairs 130, 132, 134, and lug 136 of lug portion 76 pass by the extension lugs 212 of barrel extension 50 in interdigiting fashion through receiving gaps 214. Likewise, guide flange 44 passes through a receiving gap 214. Simultaneously, extension lugs 212 pass through a corresponding gap 138 or 140 of lug portion 60.
After the lugs of bolt 34 and barrel extension 50 have passed in interdigiting fashion, bolt carrier 32 continues to move in the direction of arrow L, causing the bolt 34 to rotate about axis L and interlock the bolt 34 in a closed position. (See FIG. 1). Lug portion 76 rotates in interlock chamber 210 of barrel extension 50 as is well known in the art, causing the bolt 34 to interlock with the barrel extension 50. Once the bolt 34 is interlocked with barrel extension 50, the cartridge in firing chamber 16 may be fired by pulling trigger 24. The pulling motion on trigger 24 rotates the hammer 26 from an engaged cocked position, as shown in FIG. 1, to an unengaged position. Hammer 26 rotates to strike firing pin 28. Firing pin 28 moves within firing pin bore 36 of bolt 34 to strike the cartridge in firing chamber 16, causing the cartridge to fire.
After firing a cartridge, bolt 34 is rotated to unlock from barrel extension 50 and bolt carrier 32 recoils back in receiver 20 in a direction opposite arrow L to an open position, as shown in FIG. 1. As the bolt carrier 32 recoils, ejector pin 40 in shaft 38 is driven towards distal end 56 until it engages the spent cartridge held in cartridge recess by lip 98 of extractor 42. The operation of ejector pins is well-known in the art, and will not be discussed in detail herein. The ejector pin 40 ejects the spent cartridge by rotating the cartridge away from the cartridge recess. The rotation of the cartridge causes extractor 42 to rotate about pivot pin 114 from its first position, compressing springs 104. The extractor 42 rotates sufficiently to disengage lip 98 of extractor 42 from the rim of the cartridge. Once the cartridge is released from lip 98, springs 104 again bias extractor 42 to return to its first position. When the next cartridge is chambered, the extractor 42 again rotates from its biased first position to allow the lip 98 to engage a cartridge and releasably retain it in the cartridge recess. This operation is repeated at the discretion of the shooter to consecutively load and fire cartridges. It should be understood the present invention contemplates the use of other ejector systems known to those skilled in the art.
The firing of a cartridge in firing chamber 16 causes a recoil force in the direction opposite arrow L. Bolt lug pairs 130, 132, 134 and lug 136 bear against a corresponding interlock face of the extension lugs 212. Thus, a load bearing relationship is formed between lug pairs and the extension lugs. The force from firing the cartridge is transferred from lug portion 76 of the bolt 34 to the extension lugs 212. This force has been known to create large shear stresses at the interface between the bolt lug pairs and cylindrical body portion 66. Rapid and/or repeated firing of the cartridges is known to cause fatigue failure of the bolt lugs at this interface. The problem becomes even more severe due to the unsymmetrical pattern created by the lug pairs 130, 132, 134 and unpaired lug 136. The lack of symmetry results in an unbalanced stress distribution among the bolt lugs. As a result, first bolt lug 130a and second bolt lug 134b share a disproportionate burden of the load.
As clearly illustrated by FIG. 6 of U.S. Pat. No. 6,182,389, the disclosure of which is incorporated herein in its entirety, not only do the first and second lug bolt lugs bear a disproportionate burden of the load, they also have an extractor undercut that further structurally weakens them leading to a high failure rate. On the other hand, and as clearly illustrated in FIGS. 2 and 7 herein, the first and second bolt lugs of the preferred embodiment of the present invention are not undercut to accommodate the extractor. Moreover, the lug portion 76 is fully radiused in order to have a more even stress distribution.
The present invention also contemplates bolt lug patterns that vary from the pattern illustrated in FIGS. 2-7. In one embodiment, the bolt 34 is provided with five bolt lugs in lieu of the seven bolt lugs depicted in FIG. 7. Another embodiment contemplates nine bolt lugs. Other embodiments contemplate more or less bolt lugs as would occur to one skilled in the art.
It has also been found that the above-described configuration of extractor 42 and bolt 34 is particularly advantageous. The addition of flanges 92 to extractor 42 allows the springs 104 to be positioned on either side of firing pin bore 36. Referring to FIG. 4C, it can be observed that addition of spring stabilizing nipples 102 to the flanges 92 of extractor 42 helps to stabilize the spring against lateral motion leading to more reliable operation. The prior art springs are more susceptible to fatigue failure given their excessive lateral motion inside the spring wells 116. Additionally, the dampening of the springs using buffers 120 also reduces spring vibration thus providing more reliable operation of the extractor 42.
Preferably, the springs 104, extractor 42 and bolt 34 are manufactured from a metal material suitable for use in firearms using techniques known to those skilled in the art. Furthermore, it is preferred that bolt 34 and extractor 42 be formed from a single, unitary piece of metal; however, in alternate embodiments, bolt 34 and extractor 42 may be made by coupling two or more separate components as would occur to one skilled in the art. Also, it is contemplated that extractor 42, bolt 34, and springs 104 may be formed from different materials suitable for their intended purpose.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.
Patent Application
20080092733
