Abstract:
A fire control system for a firearm, such as a rifle, operates a bolt action for increased rate of fire and convenience while retaining the secure locking of the firing chamber by manual bolt actions. After a controller determines that a round has been fired, one or more actuators, such as electrically actuated tooth wheels or gears, unlocks and reciprocates the bolt action to extract the spent shell and to load an unfired cartridge. Thereby, a consistent locking action is achieved avoiding the inconsistent sealing of conventional automatic bolt actions. Consistent accuracy with increased firing rate operation is further achieved with a cooling system activated when the firearm exceeds an optimum temperature operating range.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains to firearms and motion converting mechanism, and more particularly, to automatic rotating and reciprocating of a bolt operating mechanism of a rifle.  
         BACKGROUND OF THE INVENTION  
         [0002]    The overwhelming majority of existing target, hunting, and sniper rifles are based on the century old Mauser system or on a various modifications thereof. The cartridge chamber of the classic Mauser system is in the form of a counterbore in the rear end of the barrel. The bolt tip is brought into contact with the end of the barrel, whereby locking takes place between the locking lugs on the bolt tip and the recesses in the receiver. The main advantage of this Mauser system is consistent setting of the cartridge in the chamber resulting in very accurate rifles. The accuracy of such manual bolt action guns has encouraged their continued use even after one hundred years of further firearm technology development. For example, most sniper units of the military, including the U.S., continue to use a manual bolt action.  
           [0003]    The biggest disadvantage of the manual bolt action is that the right hand has to cycle the action between shots, resulting in an inherently slow firing rate. In addition to the time required to cycle the action, the shooter has to aim the rifle again. Consequently, when accuracy is not paramount, semi-automatic and automatic rifles are often preferred. The rate of fire is increased because the automatic ejection of the spent cartridge and chambering of the next round occurs faster than a manual bolt action. Furthermore, the shooter tends to take less time to reacquire and aim at the target when not inconvenienced by manually cycling the bolt.  
           [0004]    Often, the bolt mechanism is comparable for both semi-automatic and automatic modes with mechanisms for triggering being altered to provide each mode. Hereinafter, both semi-automatic and automatic will generally referred to as “automatic”, referring to bolt actions that immediately cycle, utilizing the gas pressure from a fired cartridge.  
           [0005]    Several designs are well known for making a system operate in semi-automatic or automatic mode, such as U.S. Pat. No. 2,951,424 that describes a gas operated bolt and carrier system. In particular, an automatic rifle mechanisms such as the bolt and bolt carrier perform a double function. This double function consists of the primary function shared with manual bolt mechanism of locking the breach against the pressure of firing, and further consists of the secondary function of acting as a stationary piston to actuate the automatic rifle mechanism. When actuated by the pneumatic pressure from a fired cartridge, the bolt carrier rotates and thereby unlocks the bolt, carries the bolt back to open the receiver to expel the spent cartridge and return forward chambering the next cartridge and rotating to lock the bolt. The automatic rifle mechanism is able to achieve a high rate of firing (e.g., 400 rounds per minute) and outstanding reliability in many fielded firearms over the past forty years.  
           [0006]    Although adequate for many purposes, automatic rifle mechanisms inherently suffer from features that degrade accuracy in order to gain the automatic capability. In order to readily unlock and reciprocate without jamming, generally the automatic bolt mechanism does not lock as securely as the manual bolt mechanism. In particular, the automatic bolt mechanism is powered by the gas pressure from the fired cartridge and must cycle very quickly before the available energy is dissipated. Thus, firm locking is generally not practical. Thus, each chambered cartridge is not seated as securely and consistently during each firing as with a manual bolt mechanism, leading to variations in the achieved muzzle velocity, and thus the accuracy of the rifle.  
           [0007]    Thermal requirements also degrade the accuracy of automatic weapons. In particular, automatic bolt mechanisms suffer from a disadvantage related to their increased rate of fire, namely heat build-up. In order to successfully chamber rounds and expel the spent cartridges, these automatic bolt mechanisms have to accommodate the thermal expansion through the expected temperature operating range. Thus, the automatic bolt mechanism tends to require varying amounts of energy to cycle and to vary in how securely a round is chambered as a function of temperature. This additional variability further degrades the accuracy of the automatic weapon.  
           [0008]    Efforts to accommodate heat build up have generally included limiting the rate of fire, adding thermal mass to the firearm, providing more play between components for thermal expansion, and adding radiation fins to the barrel and housing. Unfortunately, limiting the rate of fire reduces the utility of the firearm, as does increasing the weight. Features such as radiating fins are also susceptible to clogging with debris that reduces their effectiveness. Moreover, for military sniper firearms, heat radiation is often an undesirable feature, allowing detection due to the infrared heat signature of the weapon. Consequently, the operator often is forced to wrap the exposed portions of the firearm in thermally insulating materials, further degrading the accuracy of the firearm and firing rate due to heat build up.  
           [0009]    Consequently, a significant need exists for a firearm that has the accuracy of those operated with a manual bolt mechanism but with the convenience and rapid firing of those operated with an automatic or semi-automatic bolt mechanism.  
         BRIEF SUMMARY OF THE INVENTION  
         [0010]    The invention overcomes the above-noted and other deficiencies of the prior art by providing a bolt mechanism that securely chambers each round to achieve the accuracy of a manual bolt mechanism, yet cycles automatically after the round has been fired to gain the convenience and increased rate of fire of an automatic or semi-automatic bolt mechanism. Separating the source of power for cycling the bolt mechanism, or action, allows for a securely sealing bolt action when locked for consistent and accurate results.  
           [0011]    In one aspect of the invention, an apparatus and method are disclosed for a bolt action firearm, such as rifle, wherein a firing controller responds to a firing command by actuating at least actuator to cycle the bolt action (i.e., unlocking, reciprocating, and re-locking) using power from a power supply. By not being dependent on the short duration of pressurized gas from a fired cartridge like conventional automatic bolt actions, a secure locking of the cartridge is achieved.  
           [0012]    In another aspect of the invention, an apparatus and method is described for enhancing the consistent and secure sealing of the bolt action by maintaining the bolt action and barrel within an optimum temperature operating range with a convection cooling system. Thereby, the tolerances between parts remain consistent by avoiding excessive contraction or expansion of metallic parts due to temperature variation.  
           [0013]    These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0014]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and, together with the general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the present invention.  
         [0015]    [0015]FIG. 1 is a side view of a bolt action firearm partially cutaway to expose a dual-actuator fire control system consistent with the present invention.  
         [0016]    [0016]FIG. 2 is a top view of the firearm of FIG. 1 partially cutaway to expose the dual actuators engaged to the bolt mechanism.  
         [0017]    [0017]FIG. 3 is a fragmentary side view of a bolt action firearm partially cutaway to expose a single-actuator fire control system consistent with the present invention.  
         [0018]    [0018]FIG. 4 is a side view of the bolt action firearm of FIG. 3 with the single-actuator fire control system in its fully open position.  
         [0019]    [0019]FIG. 5 is a side view of the bolt action firearm of FIGS. 3 and 4 with the single-actuator fire control system in its intermediate state of unlocked and closed position.  
         [0020]    [0020]FIG. 6 is a transverse vertical sectional view taken on the line of  6 - 6  of FIG. 3.  
         [0021]    [0021]FIG. 7 is a top view of a bolt action firearm incorporating a pneumatic/electric power converter for augmenting power for the fire control systems of FIGS. 1 and 3.  
         [0022]    [0022]FIG. 8 is a side view of a bolt action firearm incorporating a forced air cooling system.  
         [0023]    [0023]FIG. 9 is a transverse cross sectional view taken on the line of  9 - 9  of FIG. 8.  
         [0024]    [0024]FIG. 10 is a side view of a bolt action firearm incorporated a three-stage liquid cooling system.  
         [0025]    [0025]FIG. 11 is a transverse vertical sectional view taken on the line of  11 - 11  of FIG. 10.  
         [0026]    [0026]FIG. 12 is a sequence of steps, or routine, performed by a fire control system for automatically cycling a bolt action firearm such as depicted in FIGS. 1 and 3.  
         [0027]    [0027]FIG. 13 is a sequence of steps, or routine, performed by a temperature control system, such as depicted in FIGS. 8 and 10, for automatically maintaining a bolt action firearm within an optimum operating temperature range. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    With reference to the Drawings, wherein like numbers refer to like components through the several views, FIGS. 1 and 2 depicts a quick firing and precise firearm, depicted as a bolt action rifle  10 . Except for a fire control system  12  and related parts described in detail, the rifle  10  is or may be of generally conventional construction and comprises basically a housing or frame  14 , a gun barrel  16  threaded into a forward end of the housing  14 , and a stock  18  supporting the housing  14  and gun barrel  16 . In the upper portion of the housing  14  is an elongated bore or recess  20 , concentric with the barrel  16 , which receives a reciprocating bolt  22 , depicted in its closed and locked position relative to the housing  14 .  
         [0029]    It will be appreciated that from this position, the front end of the bolt  22  includes a relatively shallow cylindrical recess, which, in conjunction with the rear portion of the barrel bore, forms a firing chamber for holding a cartridge during the firing of the firearm  10 . The interface between the bolt  22  and the barrel  16  include an annular recess for securely gripping the rim portion of the cartridge for sealing the firing chamber. In addition, included in the bolt  22  is a suitable extractor that is engageable with the rim portion of a cartridge in the firing chamber to withdraw the shell of the cartridge after firing. Furthermore, in the housing  14  is another ejection device for expelling the shell of a spent cartridge from a receiver opening  24  in the housing  14 .  
         [0030]    The depicted firearm  10  includes a conventional manual mode. In particular, the extraction of the spent cartridge may be performed in the convention, manual fashion by rotating the bolt  22  by raising a bolt handle  26 , thereby disengaging lugs on the bolt  22  from the housing  14 , and thereafter drawing the bolt  22  backward by pulling the handle  26  aft. During the aft motion of the bolt  22 , the extractor draws the spent cartridge out of the firing chamber and the ejection device expels the shell out through the receiving opening  24 . When the handle  26  is pushed forward from its fully open rearward position, an unfired cartridge is spring fed from a magazine or other cartridge supply into the position vacated by the previously ejected shell. As the handle  26  moves forward to its forward-most closed position, the bolt  22  urges the unfired cartridge into the firing chamber. Thereafter, the handle  26  is rotated into the locked position.  
         [0031]    However, the firearm  10  advantageously includes the alternative or additional fire control system  12  for unlocking, reciprocating and re-locking the bolt  22 . To this end, the bolt  22  includes radial bolt indentations  28  that align with a radial tooth wheel  30  when the bolt  22  is in its forward-most position, abutting the barrel  16 . A locking motor  32  selectively rotates the tooth wheel  30  that engages the radial indentations  28  to thereby rotate and either lock or unlock the bolt  22 . Longitudinal bolt indentations  34  are arrayed along a portion of the length of the bolt  22 . A reciprocating motor  36  drives a toothed wheel  38  that engages the longitudinal bolt indentations  34  for cycling the bolt  22  selectively aft and forward in a reciprocating fashion.  
         [0032]    A dual actuator controller  40  sequentially activates the motors  32 ,  36  to perform the cycling of the bolt  22  in response to a trigger  42  and a fire selector control  44 , which can be in either “S” secure (“Safe”) mode, “F” fire single shot mode, or “A” automatic mode. The controller  40  is powered by a power supply  46 . In the illustrative embodiment, the controller  40  is an electronic device such as a programmable logic array, timing relay, or microcontroller having a microprocessor and is powered by an electrical battery. Similarly, the motors  32 ,  36  may be advantageously be DC electrical motors that are also powered by a battery. In other applications, the controller  40  may be electrically powered and direct another form of power to the motors  32 ,  36 , such as pneumatic pressure from a pressurized power supply. Furthermore, in the instance of a power supply such as a compressed gas container, the controller  40  may comprise an analog fluidic device that times and sequences activation of the motors  32 ,  36  through mechanical means. It should be appreciated that the form of power supply may include other types of energy storage and conversion means, such as fuel cells.  
         [0033]    It will be appreciated that the speed of actuation of the motors  32 ,  36  may be advantageously selected to reduce peak electrical current draws from the power supply  46 , and thus extend the service life of the motors  32 ,  36  and power supply  46 . For example, locking and unlocking may require a different amount of torque from reciprocating the bolt  22 , or the amount of torque may vary different portions of the rotation or the longitudinal motion. Also, the speed may be selected for user preference of one or more of the following considerations: firing rate, service life, safe motion, reduced noise, or other factors.  
         [0034]    FIGS.  3 - 6  depict a single actuator fire control system  48  that includes a single actuator controller  50  for cycling a bolt  52  similar to that described in U.S. Pat. No. 3,377,730, which is hereby incorporated by reference. The controller  50 , powered by a power supply  54 , responds to the trigger  42  by cycling the bolt  52  after a suitable delay for the round to exit the barrel  16 . With the bolt  52  closed and locked as shown in FIG. 3, the controller  50  activates a motor  56 , which in turn rotates a gear  58  that meshes with longitudinal bolt indentations  60  on the bolt  52 . Rotating the bolt  52  for locking and unlocking is accomplished by helical indentations  62  comprising the rearmost indentations  60  that engage helical teeth  64  on the gear  58 . Remaining teeth  66  on the gear  58  are transverse to engage transverse indentations  68  of the longitudinal bolt indentations  60  for reciprocating the bolt  52  aft and forward.  
         [0035]    In operation, the bolt  52  is initially closed and locked, as depicted in FIG. 3. The controller  50  causes the motor  56  to rotate the gear  58 , whose helical teeth  64  cause the bolt  52  to rotate to the unlocked position, as depicted in FIG. 4, wherein the transverse teeth  66  engage the transverse indentations  68  on the bolt  58 . Thereafter, the gear  58  is further rotated causing the bolt to traverse aft to the fully open position, extracting any cartridge in the firing chamber. Then the controller  50  causes the gear to rotate in the opposite direction, loading an unfired cartridge and locking the bolt  52 , as depicted in FIG. 3.  
         [0036]    [0036]FIG. 7 depicts a pneumatic-to-electrical power conversion mechanism  70  for the firearm  10  that may augment or wholly provide the power requirements for a fire control system  72 . Thus, the pneumatic power available from the fired cartridge is utilized; however, the power is used in a manner consistent with the aforementioned fire control systems  12 ,  48  wherein the actuation of the bolt action is delayed until after the round exits the firearm and wherein the bolt action provides a secure seal of the breech of the firing chamber. In the illustrative embodiment, the power conversion mechanism  70  is shown diagrammatically, although it will be appreciated that these features may be enclosed within the stock  18 .  
         [0037]    A gas port  74  communicates with a bore  76  of the barrel  16  to receive pressurized gas as the round exits the barrel  16 . The pressurized gas enters a forward portion  78  of a piston chamber  80 . The pressurized gas acts upon a face  82  of a piston  84 , forcing the piston  84  aft, compressing a compression spring  86 . Thereafter, the pressurized gas is allowed to exit the firearm  10  either by returning to the bore  76  or through an exhaust port  88 , allowing the mechanically stored energy in the compression spring  86  to reposition the piston  84  to its forward position.  
         [0038]    A piston rod  90 , connected to the piston  84 , meshes to an electrical generator  92  that is operated by the movement of the piston rod  90 . Electrical power from the generator  92  is stored in a capacitor  94  as a power supply or to augment a power supply for the fire control system. Alternatively, the generator may comprise a pump for compressing gas in a gas storage device for use in a pneumatically power fire control system (not shown).  
         [0039]    [0039]FIGS. 8 and 9 depict a firearm  100  that includes a convection cooling system, depicted as a forced air cooling system  102  that advantageously enhances cooling of the barrel  104  and bolt action  106  so that an increased firing rate may be maintained. A temperature controller  108  responds to a temperature signal from a temperature sensor  110  by activating a blower  112 . The blower  112  draws air from the end of the barrel  104  into a cooling jacket  114  that surrounds the barrel  104 . The barrel  104  may also include external longitudinal grooves  116  and internal air passages  118  that increase the surface area of the barrel  104  for further increasing the heat dissipation. The air expelled past the blower  112  may pass through a dispersion element  120  to muffle the sounds produced by the blow3er  112 .  
         [0040]    FIGS.  10 - 11  depict a liquid cooled firearm  130  that supports a fire control system (not depicted in FIGS.  10 - 11 ) for increased rate of fire with bolt action maintained within a desirable temperature operating range. Specifically, increased heat transfer capacity of a convection cooling system is obtained by using a liquid such as ethylene glycol. A portion of a housing  132  and barrel  134  are encompassed by a liquid cooling jacket  136  forming a liquid heat exchange passage  138  around the barrel  134 . Liquid cooling passages  140  radially spaced within the longitudinal length of the barrel  134  may advantageously communicate with the passage  138  to further enhance the heat dissipation capacity.  
         [0041]    A temperature controller  142  responds to a temperature signal from a temperature sensor  144  by pumping liquid from one or more radiators and/or liquid storage devices. In the illustrative embodiment, the controller  142  draws via tubing  146  cooling liquid from a switching station  148  that communicates with available liquid reservoirs and/or radiators, depicted as a primary radiator  150  in a forearm portion  152  of a stock  154 , a secondary radiator  156  in rear portion  158  of the stock  154 , and a remote cooling unit  160  in fluid communication with the switching block  148  via tubing  162 . The cooling unit  160  further comprises a plurality of staggered radiator units  164  through which cooling air is drawn by a blower  166 .  
         [0042]    The temperature controller  142  may advantageously activate a warming or heating element  168  in response to the sensed temperature being below the optimum temperature operating range. The heating element  168  may heat one or more of housing  14 , bolt action, firing chamber, barrel and cooling liquid. Alternatively or in addition, the temperature sensor  144  may sense both ambient temperature and the temperature of the firearm  130  and adjust the optimum temperature operating range for reducing the infrared signature of the firearm  130 .  
         [0043]    [0043]FIG. 12 depicts a sequence of steps, or routine  200 , performed by a firing control system for automatically cycling a bolt action of a firearm. With the firing control enabled (block  202 ), such as by powering the controller, a determination is made as to whether firing has been commanded (block  204 ). This determination may entail actual sensing of the round being fired or an electrical sensing of a depression of the trigger.  
         [0044]    Once firing is commanded in block  204 , the temperature of the firearm is sensed (block  206 ). Then, settings are determined for any or all of the delay time, and the unlocking, extraction, chambering, and locking speeds (block  208 ). Adjusting these settings may advantageously accommodate changes in firing time, mechanism friction and actuator performance based on temperature, type of cartridge, power supply condition, type of actuator(s), and other factors.  
         [0045]    Thereafter, the delay time is used to wait for the round to fire and to exit the firearm (block  210 ). Then, the bolt action is unlocked by rotating the bolt (e.g., helical gear enmeshing the bolt or a traversely positioned actuator to rotate the bolt) (block  212 ). Then the spent cartridge is extracted by drawing the bolt back to a fully open position (block  214 ).  
         [0046]    With the bolt fully open, the routine  200  may close and lock the bolt regardless of whether a cartridge is available in a cartridge supply such as a magazine. The routine may further chamber a round without regard to the temperature of the barrel. In the illustrative depiction of FIG. 12, a determination is advantageously made as to whether the magazine is empty (block  216 ). If not empty, then a further determination is made as to whether the temperature of the barrel is high such that chambering a round is not desirable (block  218 ). For example, an excessively hot barrel may cause a malfunction.  
         [0047]    If magazine is empty in block  216  or if the barrel is sensed to be at an unsafe temperature in block  218 , then the bolt is left open to give a visual indication to the user that the weapon is not ready to fire. If a cartridge is available in block  216  and the barrel is at a safe temperature in bloc  218 , then a cartridge is chambered by drawing the bolt forward to the closed position (block  220 ) and locking the bolt action (block  222 ).  
         [0048]    [0048]FIG. 13 depicts a sequence of steps, or routine  300 , performed by a temperature control system for maintaining a bolt action and barrel of a firearm within in optimum temperature range. With the temperature control enabled (block  302 ) such as by powering the controller, a determination is made as to whether the sensed temperature is below the operating range (block  304 ). If so, a warming element is activated (block  306 ). If the temperature is not below the operating range in block  304  or after activating the warming element in block  306 , then a determination is made as to whether the temperature is above the operating range (block  308 ). If so, a cooling system is activated (block  310 ) and processing returns to block  302 . If not above the operating temperature range in block  306 , then processing returns to block  302 .  
         [0049]    In use, a fire control system  12  of a bolt action rifle  10  responds to the firing of a cartridge by delaying for the round to exit the firearm. Then the controller  40  unlocks the bolt  22  by rotating with a power actuator, such as an electrical locking motor  32  that turns a gear meshed with radial bolt indentations  28 . The controller  40  then reciprocates the bolt  22  with an electrical reciprocating motor  36 . Accuracy further enhanced with a convection cooling system to support increased firing rate with excessive thermal build up. By virtue of the foregoing, the speed and timing of the control system  12  advantageously allows a hitherto manual bolt action to have the convenience of a gas-driven automatic bolt action without the requisite loss of accuracy.  
         [0050]    While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. For example, an open loop convection cooling system may be employed consistent with aspects of the invention wherein the user activates the cooling system. As another example, the convection cooling system may be employed on firearms other than bolt action rifles. As a further example, additional user controls may be included to allow adjusting settings for delay time, unlocking speed, extraction speed, chambering speed and locking speed. These user controls may allow selecting for maximum firing rate, for increased power supply service life, for increased service life of the firearm. These user controls may also allow for optimizing the settings for a specific type of cartridge, such as to accommodate the time required for the cartridge to fire and exit the firearm. As yet a further example, a firearm convection cooling system may be used without aspects of the invention directed to a firing control system. Similarly, the inventive firing control system may be used without a convection cooling systems. Additional advantages and modifications may readily appear to those skilled in the art.