US 20030167909 A1
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.
1. A firearm comprising:
a bolt mechanism reciprocating with respect to the barrel to load a cartridge into the barrel and to extract the cartridge from the barrel, the bolt mechanism including a locking member to rotatingly engage the barrel;
a power supply;
at least one actuator configured to unlock, reciprocate and lock the bolt mechanism when powered by the power supply; and
a controller configured to respond to a firing command by actuating the at least one actuator with the power from the power supply to unlock, reciprocate and lock the bolt mechanism.
2. The firearm of
a rotation actuator configured to rotate the bolt mechanism; and
a reciprocating actuator configured to reciprocate the bolt mechanism.
3. The firearm of
4. The firearm of
a gear including helical teeth and transverse teeth registered to the longitudinal helical and transverse indentations along the bolt mechanism; and
a motor connected to and operable to turn the gear.
5. The firearm of
6. The firearm of
7. The firearm of
8. The firearm of
9. The firearm of
10. The firearm of
a temperature sensor proximate to the barrel, wherein the controller is further configured to respond to the temperature sensor by adjusting the actuation of the at least one actuator.
11. A firearm comprising:
a bolt mechanism reciprocating with respect to the barrel to load a cartridge into the barrel and to extract the cartridge from the barrel, the bolt mechanism including a locking member to rotatingly engage the barrel;
a convection cooling system configured to direct a cooling flow to the firearm to cool the barrel and bolt mechanism.
12. The firearm of
13. The firearm of
14. The firearm of
a temperature sensor;
a temperature controller responsive to the temperature sensor to activate the convection cooling system.
15. The firearm of
16. A method of operating a bolt action firearm that includes a power supply, comprising:
in response to firing the bolt action firearm, delaying cycling a bolt action;
rotating the bolt action with power from the power supply to unlock the bolt action;
reciprocating the bolt action with power from the power supply to extract a spent cartridge and to chamber an unfired cartridge; and
rotating the bolt action with power from the power supply to lock the bolt action.
17. The method of
determining a delay time, an unlocking speed, an extraction speed, a chambering speed and a locking speed.
18. The method of
sensing temperature of the bolt action firearm; and
in response to sensing temperature exceeding an upper threshold, activating a cooling system.
19. The method of
in response to sensing temperature below a low er threshold, activating a heating element.
20. The method of
forcing cooling air around a portion of the firearm.
21. The method of
circulating cooling liquid within the firearm.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.
 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.
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.
FIG. 2 is a top view of the firearm of FIG. 1 partially cutaway to expose the dual actuators engaged to the bolt mechanism.
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.
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.
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.
FIG. 6 is a transverse vertical sectional view taken on the line of 6-6 of FIG. 3.
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.
FIG. 8 is a side view of a bolt action firearm incorporating a forced air cooling system.
FIG. 9 is a transverse cross sectional view taken on the line of 9-9 of FIG. 8.
FIG. 10 is a side view of a bolt action firearm incorporated a three-stage liquid cooling system.
FIG. 11 is a transverse vertical sectional view taken on the line of 11-11 of FIG. 10.
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.
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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
 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.
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.
 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.
 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).
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.
 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.
 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.
 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.
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.
 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.
 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).
 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.
 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).
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.
 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.
 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.