Abstract:
A counting mechanism for detecting and registering the number of rounds fired from a recoil gun includes a housing that can be mounted to a component of the gun that exhibits recoil motion upon firing of a round. A counting device is contained within the housing and includes an actuator that is activated by the recoil motion of the gun component upon a round being discharged. A weighted mass is movable within the housing with the recoil motion of the gun component, and the actuator is operably configured with the mass such that movement of the mass resulting from the recoil motion actuates the actuator and increments the counting device.

Description:
PRIORITY CLAIM 
       [0001]    The present application claims priority to Provisional Application Ser. No. 60/633,189 filed Dec. 3, 2004. 
     
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to the field of devices that count projectiles fired from gun, and more specifically to counters used to track the number of rounds fired from a large caliber gun, such as a cannon or artillery piece. 
       BACKGROUND OF THE INVENTION 
       [0003]    There are various reasons for counting and tracking the number of rounds fired from a gun or large caliber armament piece. Inventory control of ammunition, maintenance schedules, personnel training, and so forth, are generally all a factor of the number of rounds discharged from the weapon. For larger caliber pieces, such as field cannons, artillery pieces, and ship mounted guns, the barrel of the weapon is generally limited to a specified number of uses, and it is important from operational and safety considerations not to exceed this specified number. 
         [0004]    In this regard, various mechanical and electrical counter devices have been described in the art for the purpose of tracking the number of rounds fired from a piece of armament. For example, U.S. Pat. Nos. 4,102,074 and 4,146,987 describe an impulse activated counter for weapons that includes an actuator having a reactive weight with an eccentric center of mass. The weight is freely rotatable in a plane within preset limits in response to an externally applied impulse force. The weight applies a torque force to a shaft that, in turn, activates the counter. Means are provided to apply a counter torque to the weight so that the counter is actuated only in response to a resultant torque of a predetermined magnitude generated by the impulse. 
         [0005]    U.S. Pat. No. 3,453,882 describes a device to determine when a projectile emerges from the muzzle of a gun. The device records the signal from an electrical circuit containing a photo-duo-diode located in a radial hole near the muzzle of the gun. The signal is recorded as a reference along with a time base, gun chamber pressure, and other data. 
         [0006]    The device of U.S. Pat. No. 3,552,053 counts shots fired from a gun by way of a piezo-electric crystal that is clamped to the barrel of the gun. Upon discharge of a shot, the crystal is stressed by transient radial expansion of the barrel and produces an electrical output pulse that is sensed by a threshold detector and counted in a register. U.S. Pat. No. 6,817,239 describes another device that utilizes a piezofilm sensor integrated into a circuit board mounted onto a gun. The piezofilm sensor is deformed by the impulse recoil of the gun and emits a signal to a chip contained in the circuit board, which records the impulse as a count. 
         [0007]    U.S. Pat. No. 3,792,638 describes a fluidic artillery round counter that measures the zone charge used to fire the artillery rounds. The device includes a check valve, a capacitance volume, a regulator, a fluidic oscillator, and a counter whose output is fed into a mechanical summing register. The check valve is connected to the gun bore through a small tube, and gas from the gun bore is the actuating source for the device. 
         [0008]    Although the above cited patents have suggested various types of counters, the need still exists for a highly reliable yet simple counting mechanism that can withstand the rigors and extreme conditions of a battlefield environment. This need is particularly acute for large caliber guns, such as cannons and artillery pieces. 
       SUMMARY OF THE INVENTION 
       [0009]    Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
         [0010]    In accordance with the invention, a rugged and reliable counting mechanism is provided for detecting and counting the number of rounds fired from a recoil gun. The mechanism is simple in design and can withstand the rigors and extreme conditions of a battlefield. Although having particular usefulness for large caliber recoil guns, such as cannons, artillery pieces, and shipboard gun mount systems, the counting mechanism may be used with any weapon or armament piece that exhibits a recoil upon discharge of a round. 
         [0011]    The counting mechanism utilizes the inertia of a mass and the acceleration of the recoil event to increment a counter. Each time the gun is fired, the barrel experiences an intense recoil action. Other components of the gun may also experience the recoil and, although it is preferred to mount the counting mechanism to the barrel, it is within the scope and spirit of the invention to mount the inventive counting mechanism to any component of the gun that exhibits a recoil action upon firing a round. The recoil action constitutes a large acceleration component and, in conjunction with a mass, this acceleration can be converted into a force used to increment a counter. 
         [0012]    In a particular embodiment of the counting mechanism, a housing is provided with a shape and configuration for mounting to a barrel of the gun, or another component of the gun that experiences the recoil action. The housing may take on any size and shape, and may include a base member and a cover member that is sealed to the base member to protect the internal components of the mechanism. A counting device is contained within the housing and includes an actuator that is activated (i.e., incremented) by the recoil action of the gun component upon a round being fired from the gun. A weighted mass is movable within the housing in response to the recoil motion of the gun component, and the actuator is operably configured with this movable mass such that relative movement between the mass and housing upon discharge of a round produces an increment to the counting device. 
         [0013]    The counting device mechanism may contain any manner of conventional mechanically incremented counter. For example, the counter may be a geared incrementing counter having a cam or gear that is incremented by the actuator, and which in turn increments downstream read-out gears. The read-out gears sequentially increment as discharge events are registered by the counting mechanism. In one embodiment, the counter and its associated actuator may be fixedly mounted within the housing, and a separate weighted mass is movable within the housing. Upon a recoil action, relative movement between the weighted mass and the housing causes the mass to engage the actuator, which results in indexing of the counter. 
         [0014]    In an alternate embodiment that requires fewer components and takes advantage of the weight of certain components of the counting device, the counter is movably mounted within the housing and also functions as the weighted mass. For example, the counter may be linearly slidable within the housing and have friction reducing sliders for this purpose. The counter includes an actuator that is triggered to index the counter upon the counter moving to a defined position within the housing, for example by contacting structure within the housing as the counter moves. In an embodiment wherein the actuator moves in a plane generally transverse to movement of the counter, the actuator may be driven in this transverse direction by engagement with a cam track defined within the housing. It should be appreciated that any number of configurations and transfer devices may be utilized to transfer movement of the weighted mass relative to the housing to the actuator. 
         [0015]    A spring or other suitable resilient device may be disposed within the housing to oppose the relative movement of the weighted mass in response to the recoil action of the gun component. In addition, a stop or bumper may be disposed on the side of the weighted mass opposite from the spring to arrest return movement of the weighted mass. The weighted mass may be held between the spring and bumper in an “at rest” position, and any movement of the weighted mass in response to the recoil is in opposition to the spring. The spring is selected as a function of the weight of the weighted mass and intensity of the recoil action, and desirably is stiff enough to ensure that only the intensity of the recoil action will result in indexing of the counter. The spring also serves to protect the counting mechanism from the full impulse load of the gun recoil. In this regard, the spring may be selected so as to continuously compress during the entire recoil event. The spring also stores energy that is used to return the weighted mass to its at-rest position after the recoil event. 
         [0016]    The counting device also includes a visual display of the total count of rounds fired. This display may be external to the housing, or contained within the housing and externally viewable through a window in the housing. In the embodiment wherein the counter constitutes the weighted mass, the display may be a feature of the counter and visible through a window in the housing in the at-rest position of the counter. 
         [0017]    Aspects of the invention will be described in greater detail below with reference to a particular embodiment illustrated in the drawings. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0018]      FIG. 1A  is a perspective view of a tank having an embodiment of the inventive counting mechanism mounted at the muzzle of the tank&#39;s gun bore. 
           [0019]      FIG. 1B  is an enlarged perspective view of the muzzle end of the gun bore taken from  FIG. 1A . 
           [0020]      FIG. 2  is a front perspective view of an embodiment of the counting mechanism. 
           [0021]      FIG. 3  is a back perspective view of an embodiment of the counting mechanism. 
           [0022]      FIG. 4  is a front perspective view of the embodiment of  FIG. 3  with the housing cover removed to reveal the internal components of the counting mechanism. 
           [0023]      FIG. 5  is a perspective view of the base member of the housing from the embodiment of  FIG. 4  with the internal components removed. 
           [0024]      FIG. 6  is a front perspective view of a geared incrementing counter that may be used with the counting mechanism. 
           [0025]      FIG. 7  is an alternate perspective view of the counter of  FIG. 6  particularly illustrating the actuator mechanism. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Reference will now be made in detail to examples of the invention, one or more embodiments of which are illustrated in the figures. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. It is intended that these and other modifications and variations be included within the scope and spirit of the invention. 
         [0027]    Referring to the figures in general, an embodiment of a counting mechanism  10  in accordance with the invention is illustrated. In  FIGS. 1A and 1B , the mechanism  10  is illustrated mounted to a tank gun  12 . The device  10  is mounted to the barrel  14  near the muzzle  16 . Referring to  FIG. 1B , it can be seen that this particular embodiment  10  is mounted to the gun sight  18  at the muzzle  16 . As discussed in further detail below, the device  10  includes a mounting flange  36  for conveniently mounting the device  10  to any component of the gun  12  or artillery piece that experiences recoil action. It should be understood that the device  10  may be mounted to any conventional gun, armament, or other weapon that experiences recoil action upon firing of a round. Additionally, the device  10  need not necessarily be mounted on the gun barrel  14 , but may be mounted to any part of the weapon or gun that experiences the recoil action. 
         [0028]    In the illustrated embodiment, the counting mechanism  10  includes a housing  20  having a shape and configuration for mounting to a component of the gun, for example on the barrel  14  as illustrated in  FIGS. 1A and 1B . The housing  20  is not limited by its shape or size, so long as the housing  20  can be readily accommodated on the gun component. The housing  20  may include multiple components, such as a back member  22  and a cover member  24 . The cover member  24  may be sealed to the back member  22  by conventional means, such as screws or rivets  26 , adhesive, welding, and so forth. The internal components of the counting mechanism  10  are contained within the interior volume defined by the back member  22  and cover member  24 . It may be desired that the cover member  24  be sealed with respect to the back member  22 , and any conventional sealing device or means may be utilized for this purpose. For example, referring to  FIG. 4 , a seal groove  34  may be defined in either or both of the back member  22  and front member  24 , and any conventional seal or gasket material may be seated within the groove  34 . In this way, when the front member  24  and back member  22  are joined together, a hermetic seal is formed between the components to protect the internal working components from the rigors of the battlefield environment. 
         [0029]    The counting mechanism  10  may be mounted to the gun component by any suitable means. In the illustrated embodiment, the mechanism  10  includes a mounting flange  36  extending from the back housing member  22 . The flange  36  may be an integral component of the back member  22 , or a separate component joined to the housing  20 . The mounting flange  36  includes mounting holes  40  that may be used to directly attach the device  10  to the gun component. For example, in the embodiment illustrated in  FIG. 1   b , the mounting flange  36  is bolted onto the base of the gun sight  18 . It should be appreciated that the mechanism by which the counting mechanism  10  is mounted to the gun component is not a limiting feature. 
         [0030]    A counting device, generally  46 , is contained within the housing  20  and includes an actuator  48  that activates (i.e. increments) the counting device  46  for each recoil action of the gun component. An embodiment of the counting device  46  will be described in greater detail below. 
         [0031]    A weighted mass, generally  50 , is contained within the housing  20  and is movable relative to the housing in response to recoil action of the gun component. Means are provided for transferring relative movement of the weighted mass to the counting device to increment the device in response to the recoil action. For example, in a particular embodiment, the weighted mass  50  is operably configured with the actuator  48  and counting device  46  such that relative movement between the housing and weighted mass  50  upon discharge of a round from the gun results in triggering of the actuator and an increment to the counting device  46 . The weighted mass  50  may be virtually any weighted component within the housing  20 . For example, in one particular embodiment, the weighted mass  50  may be a separate component from the counting device  46  and, upon experiencing the recoil action, relative movement between the weighted mass  50  and the housing  20  causes the mass to engage the actuator  48  of the counting device  46 . In this particular embodiment, the counting device  46  and actuator  48  may be stationarily mounted within the housing. 
         [0032]    In the illustrated embodiment, the weighted mass  50  is actually one or more of the components of the counting device  46 . Thus, it should be understood that the weighted mass  50  need not be a separate component from the counting device, and may include all or a portion of the components of the counting device  46 . For example, the counting device  46  has a distinct weight and mass and may be movably mounted within the housing  20  so as to be slidable in a given direction relative to the housing  20  upon the gun component experiencing the recoil action. The actuator  48  moves with the counting device  46  and, at a certain position of the counting device  46 , may engage stationary structure within the housing  20  that causes the actuator  48  to increment the counting device  46 . 
         [0033]    An embodiment of the movable counting device  46  is illustrated in the figures. In this embodiment, the counting device  46  includes a mechanically incremented counter, such as the geared counter  52 . The geared counter  52  includes a frame  54  having a plurality of read-out gears  68  that are geared together and sequentially advanced by actuation of a cam wheel  64 . In the illustrated embodiment, the counter  52  includes four readout gears  68 . However, the number of read-out gears can be varied depending on the desired maximum number of counts. The read-out gears  68  have the numbers 0 to 9 printed or otherwise displayed on the round cylindrical portion of the gear. The numbers make up a visual display  74  that is visible through a window  38  in a portion of the housing, such as the front cover  24  as illustrated in  FIG. 2 . 
         [0034]    Operation of the type of geared counter  52  illustrated in the figures is well known and need not be described in great detail herein. In general, each of the read-out gears  68  have a set of gear teeth on each side of the cylinder body. One set of teeth is incremented and the other set increments an adjacent gear. Each time a readout gear  68  is incremented, that particular gear  68  increments a respective carry-out gear that “carries” the 1 of a 9 to 10 transition to the next decimal place (i.e. the next read-out gear). The carry-out gears also have two sets of teeth. The first set, which is incremented by the respective read-out gear, has  20  teeth. The second set, which increments the next decimal place read-out gear at a 9 to 0 transition, has only two teeth. Therefore, for each ten increments from the previous read-out gear, the following read-out gear is incremented by one. 
         [0035]    The counter  52  may be slidably contained within the housing  20  in numerous ways. In the illustrated embodiment, the counter  52  includes sliders  56  at one or more locations on the frame  54 . The sliders  56  slide along a glide surface  32  ( FIG. 5 ) defined in the housing back member  22 . The sliders  56  are essentially bearing surfaces that make contact with the glide surface  32  and are used to decrease friction between the moving components. The sliders  56  may be made of, for example, bronze. 
         [0036]    In the embodiment wherein the weighted mass constitutes the geared counter  52 , the actuator  48  includes an indexer  58  that is slidable on the counter frame  54  in a direction generally transverse to the axis of the counter  52  and sliding direction of the counter  52  within the housing  20 . The indexer  58  includes an indexing tab  62  that engages with the cam wheel  64 . Displacement of the indexer  58  thus causes an incrementing of the counter  52 . 
         [0037]    The relative linear sliding motion of the counter  52  may be transferred to the indexer  58  by various means. In the illustrated embodiment, the indexer  58  includes a pin  60  that engages between cam tracks  42  defined on the housing back member  22 , as seen in  FIG. 5 . The cam tracks  42  define an angled path such that linear moment of the counter  52  within the housing  20  causes the indexer  58  to move from an at-rest position to an indexing position. Return movement of the counter  52  causes the indexer  58  to return to its at-rest position. It should be appreciated that the indexer  58  may be disposed so as to be actuated linearly along the same line of motion as the counter  52  within the housing  20 . Any manner of structure or stop device within the housing may engage the indexer  58  and cause the indexer  58  to move in to its incrementing position. 
         [0038]    A resilient device  70 , such as a spring, may be disposed within the housing  20  to oppose movement of the weighted mass  50  in response to the recoil action of the gun component. In the illustrated embodiment, the spring  70  is held in position by way of a positioning member  71  ( FIG. 3 ) fitted into a groove  30  ( FIG. 5 ). The positioning member  71  includes an end that extends into the spring  70  and thus retains the spring in position relative to the housing  20 . Similarly, a positioning member  77  ( FIG. 6 ) may be provided on the counter frame  54  that engages in the opposite end of the spring  70 . In this way, the spring is positively retained between the housing  20  and movable counter  52  (or other weighted mass  50 ). 
         [0039]    In addition, a stop or bumper  72  ( FIG. 4 ) may be provided at the opposite end of the weighted mass  50 . The bumper  72  may comprise any resilient material and may include a supporting body  73  with a positioning member  75  engaged in a correspondingly shaped groove  28  ( FIG. 5 ) defined in the back cover  22 . The bumper  72  is provided to arrest the return movement of the weighted mass  50 . Referring to  FIG. 4 , it is thus seen that the weighted mass  50  (i.e. the movable counter  52 ) is held between the spring  70  and bumper  72  in an “at-rest” position, and any movement of the weighted mass  50  in response to the recoil action of the gun is in opposition to the spring  70 . The spring  70  is thus selected as a function of the weight of the weighted mass  50  and the anticipated intensity of the recoil action. The spring  70  is desirably stiff enough to ensure that only the intensity of the recoil action will result in indexing of the counter  52 . The spring  70  also serves to protect the counting device from the full impulse load of the gun recoil. In this regard, the spring  70  may be selected so as to continuously compress with movement of the weighted mass  50  during the entire recoil event. The spring  70  also stores the energy used to return the weighted mass  50  to its at-rest position after the recoil event. 
         [0040]    In operation, when the gun is fired, the recoil action of the gun barrel  14  forces the housing  20  into the movable counter  52  (or other weighted mass), which causes compression of the spring  70 . As the spring  70  is compressed, the recoil impulse of the gun is spread out over the duration of compression and the pin  60  on the indexer  58  travels through the cam tracks  42  defined on the housing back member  22 . As the pin  60  moves through the cam tracks  42 , the indexer  58  is moved in a transverse direction, which causes an incrementing of the cam wheel  64 . 
         [0041]    It should be appreciated by those skilled in the art that various modifications and variations can be made to the embodiment of the invention described and illustrated herein without departing from the scope and spirit of the invention. It is intended that the invention include such modifications and variations as come within the scope of the appended claims and their equivalents.