Patent Publication Number: US-11029116-B2

Title: Trigger mechanism for firearms

Description:
RELATED APPLICATION 
     This application is a Non-provisional application claiming priority to U.S. Provisional Patent Application No. 62/792,593, filed Jan. 15, 2019, and incorporates the same herein by reference. 
    
    
     TECHNICAL FIELD 
     This invention relates to a trigger mechanism for use in a firearm. More particularly, it relates to a trigger mechanism for use in a bolt-action rifle. 
     BACKGROUND 
     Bolt-action rifles are particularly suited for long-range and/or precision shooting because the barreled action may be firmly supported in a stock or chassis and firing requires minimal movement of a minimum number of parts. Additionally, because the action is cycled manually, all of the energy produced by the burning propellant powder is used to accelerate the projectile in the barrel and there are no automatically cycled parts moving that may transmit vibrations to other parts of the firearm. 
     A variety of trigger mechanisms have been proposed, designed, and made for bolt-action rifles. For any such trigger mechanism, it is imperative that the cocked striker inside the bolt be released every time the trigger is pulled and that it never be released unless the trigger is pulled. Various designs have been proposed to ensure such safety. However, in recent years, even widely used designs have been found to be unsafe and to allow an unintended discharge under certain conditions. 
     For precision shooting, it is desirable to have a trigger mechanism requiring minimal movement of the trigger and an ability to adjust the amount of force required to pull the trigger. The trigger mechanism needs to release with a crisp “break” with minimal internal friction as the mechanism&#39;s parts move relative to each other. 
     SUMMARY OF THE INVENTION 
     The present invention provides a trigger mechanism for a bolt-action firearm with a manual safety, minimal trigger pull length, externally adjustable trigger force, and a bolt-release mechanism that is captive to the trigger assembly. The mechanism utilizes a double over-center linkage to minimize internal friction and ensure safety by precluding unintended discharge by any other means. 
     The trigger mechanism includes a housing with a trigger member pivotally mounted therein. The trigger member is movable between set and pulled positions. A trigger dog is pivotally mounted in the housing and has a first lever arm portion engaged to a lever arm portion of the trigger member by a first over-center linkage. A striker dog is pivotally mounted in the housing and is movable between set and released positions. The striker dog has a lever arm portion engaged to a second lever arm portion of the trigger dog by a second over-center linkage. The over-center linkages are configured to inhibit rotation of the striker dog from the set position to the released position until the trigger member is manipulated from the set position to the pulled position with a force greater than an engagement threshold of the over-center linkages. 
     Other aspects, features, benefits, and advantages of the present invention will become apparent to a person of skill in the art from the detailed description of various embodiments with reference to the accompanying drawing figures, all of which comprise part of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Like reference numerals are used to indicate like parts throughout the various drawing figures, wherein: 
         FIG. 1  is a first isometric view of a trigger mechanism assembly according to one embodiment of the present invention; 
         FIG. 2  is a second isometric view thereof; 
         FIG. 3  is a third isometric view thereof; 
         FIG. 4  is a fourth isometric view thereof, with safety detents shown in an exploded position; 
         FIG. 5  is a right side sectional view of the mechanism in a SAFE condition; 
         FIG. 6  is a similar view with the manual safety moved to the FIRE position; 
         FIG. 7  is a similar view showing the position of internal components after the trigger has been pulled; 
         FIG. 8  is an isometric view of the assembly showing the captive bolt release mechanism; 
         FIG. 9  is a similar view with the captive bolt release mechanism in an exploded position; 
         FIG. 10  is an exploded isometric view of the manual safety lever and detents; and 
         FIG. 11  is a fragmentary sectional view showing the safety lever detents. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the drawing figures, this section describes particular embodiments and their detailed construction and operation. Throughout the specification, reference to “one embodiment,” “an embodiment,” or “some embodiments” means that a particular described feature, structure, or characteristic may be included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” or “in some embodiments” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the described features, structures, and characteristics may be combined in any suitable manner in one or more embodiments. In view of the disclosure herein, those skilled in the art will recognize that the various embodiments can be practiced without one or more of the specific details or with other methods, components, materials, or the like. In some instances, well-known structures, materials, or operations are not shown or not described in detail to avoid obscuring aspects of the embodiments. “Forward” will indicate the direction of the muzzle and the direction in which projectiles are fired, while “rearward” will indicate the opposite direction. “Lateral” or “transverse” indicates a side-to-side direction generally perpendicular to the axis of the barrel. Although firearms may be used in any orientation, “left” and “right” will generally indicate the sides according to the user&#39;s orientation, “top” or “up” will be the upward direction when the firearm is gripped in the ordinary manner. As used herein, “firearm” can encompass air guns, muzzle-loading arms, and/or other similar devices. 
     Referring first to  FIGS. 1-4 , therein is shown at  10  a trigger assembly according to one embodiment of the invention. While the invention may be adapted to most any bolt-action pattern, the illustrated embodiment is configured to fit the popular Remington  700  pattern receiver. The entire mechanism of the trigger assembly  10  is supported by a housing  12 . The housing  12  may be milled from a billet of suitable material, such as steel or an aluminum alloy, may be cast in metal or suitable polymer material, may be “printed” by an additive machining process, or may be assembled from components into a unitary part. The housing  12  (and, thereby, the entire trigger assembly  10 ) is attached to the receiver and/or stock using assembly pins (not shown) that pass through openings  14  near the top of the housing  12 . Unlike some other designs, the assembly pins in this embodiment are not used to support any other parts of the trigger mechanism or to act as a pivot axle. As will be described later in greater detail, the housing  12  pivotally supports a trigger member  16  and a manual safety  18 . As best shown in  FIG. 3 , on the left side of the housing  12 , a bolt stop  20  and release lever  22  are mounted captive to the assembly  10 . This configuration allows the trigger assembly  10  to be a complete “drop-in” unit without separate parts that require further assembly during installation. 
     Referring now also to  FIG. 5 , four moving parts are supported on pivot axles (pins) within and between sidewalls of the housing  12 . The trigger member  16  includes a finger lever  24 , which may be of any desired style or shape. The trigger member  16  is pivotally supported on a trigger pin  26  that extends through aligned opposite openings  28  in sidewalls of the housing  12 . The trigger member  16  includes a spring finger portion  30  that extends generally upwardly and forward to engage one or more trigger springs  32 . The trigger springs  32  are received in partially threaded bores  34  so that one end is in contact with the spring finger portion  30 . This portion of the housing  12  serves to connect the sidewalls so that the housing  12  is generally open to the front above it, generally open to the bottom behind it, and generally open to the rear and top. The springs  32  bear against the spring finger portion  30  to bias the trigger member  16  toward a reset position (shown in  FIG. 5 ). A stop pin  35  limits the travel of the trigger  16  toward the reset position. Compression force of the springs  32  against the spring finger  30  may be adjusted, such as with threaded set screws  36  and/or by selecting springs  32  having a different compression force. The set screws  36  may be adjusted, such as with a hex wrench, while the trigger assembly  10  is installed on a receiver and in a stock or chassis via the gap left within the trigger guard that provides access to the bolt stop release lever  22  (see  FIGS. 8 and 9 ). The springs  32  may be adjusted and/or replaced individually to provide a user-selected trigger pull weight from a few ounces to a few pounds. Extending generally upward above the trigger pin  26 , the trigger member  16  includes a trigger lever arm portion  38 . 
     A trigger dog  40  is situated within the housing  12 , generally above the trigger member  16 , and is pivotally supported on a pivot pin  42  that extends between opposite openings  44  in sidewalls of the housing  12 . The trigger dog  40  includes a socket  46  that receives a lobe of the lever arm portion  38  of the trigger member  16  and acts as a first lever arm portion. Opposite the socket  46 , the trigger dog  40  has a second lever arm portion  48  that extends radially away from the pivot pin  42  a significantly greater distance than is the socket  46  from the pivot pin  42 . A tension spring  58  anchored to the housing  12  by a cross pin  52  is attached to the lever arm portion  48  of the trigger dog  40  and biases it toward a reset position (clockwise, as viewed in  FIG. 5 ). 
     Near the top of the housing  12 , a striker dog  54  is pivotally mounted on a pivot pin  56  which extends between openings  58  in sidewalls of the housing  12 . The striker dog includes a striker-engaging portion  60  which extends radially from the pivot pin  56  in a generally rearward direction. The striker dog  54  is in the form of a “Class 3 lever” (i.e., a lever in which the effort is between the fulcrum and the load). The manner in which the striker engaging portion  60  interacts with the striker of a bolt-action firearm is well-known. The heavy forward spring force of the striker will push the striker dog  54  down as soon as upward support is removed. A stop pin  62  located generally forward of the striker dog  54  engages a notch  64  to limit its pivotal movement. 
     Unlike many other designs, the manual safety mechanism in this embodiment is supported inside the housing  12 . The manual safety lever  18  includes a handle  66  that project to the exterior of the stock or chassis for manipulation by the user. A body portion  68  is situated within the housing  12  and pivotally mounted on a pivot pin  70  that extends between laterally aligned openings  72  in the sidewalls of the housing  12 . The body portion  68  has a lower lobe  74  that engages a socket  76  in the trigger member  16  when in the SAFE position (shown in  FIG. 5 ). An upper lob  78  of the body portion  68  acts as a stop for a safety finger  80  that extends from the trigger dog  40  while in the SAFE position. In the SAFE condition, the trigger  16  and trigger dog  40  are both mechanically blocked against any movement from the reset position. In turn, the striker dog  54  is mechanically blocked from movement by the trigger dog  40 . The relatively larger diameter of the component pivot pins  26 ,  42 ,  56 ,  70  reduces friction and facilitates rotation. 
     Referring now to  FIG. 6 , when the handle  66  of the manual safety lever  18  is pushed forward, the body portion  68  is rotated (as shown by an arrow) to the FIRE position. When rotated as shown, the lower lobe  74  of the body portion  68  is moved out of the socket  76  of the trigger member  16 . A small but adequate gap  82  is left to allow pivotal movement of the trigger member  16 . Likewise, the upper lobe  78  of the body portion  68  is moved away from blocking contact with the safety finger  80  of the trigger dog  40 . 
     Referring still to  FIG. 6 , the trigger actuation mechanism provides a double over-center lock-up and release feature. As shown by centerline R 1 , the center point of the trigger&#39;s lever arm portion  38  is off of the centerline between pivot points of the trigger member  16  and trigger dog  40 . Rotation requires that the center point cross the centerline R 1 , exceeding an engagement threshold necessary to pass the dead-center point. Likewise, the center point of the trigger dog&#39;s lever arm portion  48  is off the centerline (R 2 ) between the lever arm portion  48  and the release shoulder of the socket  84  in the striker dog  54 . Thus, even when the manual safety lever  18  is in the FIRE position, more than the force of the trigger springs  32  is holding all three members  16 ,  40 ,  54  in the reset position. Two separate over-center linkages must be displaced for the striker dog  54  to release the striker. This can provide an additional degree of safety not found in other trigger designs. 
     Referring now, by comparison, to  FIG. 7 , when the finger lever  24  of the trigger member  16  is pulled to the rear (shown by an arrow), rotation of the trigger member  16  rolls the lever arm  38  out of the socket  46  of the trigger dog  40  as the trigger dog  40  is rotated in an opposite direction (see rotational arrows in  FIG. 7 ). As the trigger dog  40  rotates (counter-clockwise as shown in  FIG. 7 .), the lever arm portion  48  slides over the shoulder of the striker dog socket  84 , allowing the striker dog  84  to rotate, collapsing under the force of the striker, which is released. In the illustrated embodiment, the end of the finger lever  24  need move only 0.035 inch (about 1.2 degrees of rotation) from “reset” to “fire.” 
     The force of the striker bearing against the engaging portion  60  of the striker dog  54  causes both the striker dog  54  and trigger dog  40  to “collapse” and rotate to their limits. The tension of the trigger dog spring  56  is readily overcome and the trigger dog  40  is free to continue rotation past the centerline R 2  or “break” point. Movement of the trigger dog  40  is limited only by the bolt release pivot pin  86 , to be described later. Movement of the striker dog  54  is limited by the notch  64  and pin  62 . Once the striker is released and is no longer pushing the striker dog  54  down, the tension of the trigger dog spring  50  returns the trigger dog  40  back toward its reset position, which lifts the striker dog  54 . Release of finger pressure on the trigger member  16  allows the trigger springs  32  to rotate it back toward its reset position. This rotation rolls the lobe of the lever arm portion  38  into the socket  46  of the trigger dog and reseats the lobe of the trigger dog&#39;s lever arm portion  48  into the socket  84  of the striker dog  54  (which acts as a lever arm portion of the striker dog  54 ), returning the linkage to its double over-center reset position (shown in  FIG. 6 ). The striker is then re-cocked by manually cycling the bolt. 
     Referring now to  FIGS. 8 and 9 , therein is shown the bolt stop and release mechanism that can be made captive to the housing  12  so that the trigger assembly  10  may be installed as a “drop-in” unit. The bolt stop pivot pin  86  extends through both sidewalls of the housing  12  and outwardly therefrom to the left a distance as may be required by the particular model of receiver or firearm into which the trigger assembly  10  is being installed. The bolt stop  20  is pivotally mounted on the bolt release pivot pin  86  between snap rings  88  that fit into annular grooves  90  in the bolt release pivot pin  86 . A torsion spring  92  is provided to bias a forward portion of the bolt stop  20  up, toward an engaged position. The release lever  22  includes elongated openings  94 ,  96  that fit over a detent boss  98  that extends from the left side of the housing  12  and a protruding portion of the trigger pivot pin  26 . The release lever  22  is retained on the detent boss  98  by a snap ring  100  that engages an annular groove  102  on the detent boss  98 . 
     When the release lever  22  is pushed upwardly, the elongated openings  94 ,  96  will slide along the detent boss  98  and protrusion of the trigger pivot pin  26 . A slightly skewed orientation of one or both of the elongated openings  94 ,  96  will cause the release lever  22  to rotate as it slides, allowing the lateral finger  104  that engages a rear portion of the bolt stop  20  to follow the pivotal movement or “swing” of the bolt stop  20 . Because the bolt release system is retained to the housing, installation of the unit  10  requires only insertion of the assembly pins through the assembly pin openings  14  of the housing without any loose parts. The only adjustment to be made is to the trigger springs  32  (weight of pull), which can be accessed either before or after assembly to the receiver and installation into a stock or chassis. Some custom receivers use a different bolt release mechanism that is integrated into the receiver. For such installations, the bolt catch  20 , spring  92 , lever  22 , and snap rings  88 ,  100  can simply be removed and not used. 
     Referring now to  FIG. 10 , therein is shown an exploded isometric view of the manual safety lever  18 , pivot pin  70 , and detent mechanism relative to the housing  12 . The detent mechanism releasably holds the manual safety lever  18  in either the SAFE or FIRE position. Referring also to  FIG. 11 , each detent mechanism includes a detent ball  106 ,  108 , a detent ball cup  110 ,  112 , and a detent spring  114 ,  116 . Each mechanism is received in a socket  118 ,  120  and held in place by an internal snap ring  122 ,  124  seated in an annular internal groove  126 ,  128 . The detent ball cups  110 ,  112  can be in the form of simple washers and the detent springs  114 ,  116  can be wave springs (flat wire compression springs). When assembled, the springs  114 ,  116  press the detent balls  106 ,  108  toward the body portion  68  of the manual safety lever  18 . Each ball  106 ,  108  will seat in a respective detent socket  130 ,  132  in the body portion  68  in the respective SAFE or FIRE position. In the illustrated embodiment, the detent for the SAFE position is on the left side and the detent for the FIRE position is on the right side. These could be reversed or modified to be combined on one side, including using a single detent ball with two detent sockets, or two detent balls with one detent socket. 
     While one or more embodiments of the present invention have been described in detail, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. Therefore, the foregoing is intended only to be illustrative of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended to limit the invention to the exact construction and operation shown and described. Accordingly, all suitable modifications and equivalents may be included and considered to fall within the scope of the invention, defined by the following claim or claims.