Abstract:
The high cycle rate transfer device invention disclosed herein enables a continuous conveyance of material in a limited space envelope. Particularly, a roller chain is driven by a center sprocket with outboard rollers on the chain running in a track so that material can be moved in both directions. Pawls on each end of the chain are used to urge the material. Each time the chain is moved, a pawl folding and unfolding mechanism maintains the pawls in a proper position and timed relation to each other.

Description:
FIELD OF THE INVENTION 
     The present invention provides a high cycle rate transfer device for material handling. The device employs cams and connections with a plurality of pawls moving continuously to transfer materials. The invention provides a high cycle and energy efficient material transfer system which is operable in a limited space envelope. 
     SUMMARY OF THE INVENTION 
     The high cycle rate transfer device utilizes a fixed length chain with a folding pawl on each end. The chain has outboard rollers which run in a track to provide lateral support and is driven by a sprocket. When the sprocket is driven one pawl unfolds to urge the material while the other pawl is folded in, and temporarily out of the way, to let the material through. The folding and unfolding mechanisms keep the pawls in a proper position and in a timed relation to each other. 
     Specific advances, features and advantages of the present invention will become apparent upon examination of the following description and drawings dealing with several specific embodiments thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of the high cycle rate transfer device showing material (rounds of ammunition) being transferred from a lower position to a final hoisted position. Pawls are shown in extended and unfolded position. The pawl on the right is also shown in its folded and stowed position (phantom lines). 
     FIG. 2 is a section taken along line 2--2 of FIG. 1, showing a portion of a magazine drum and a plan view of the high cycle rate transfer device. Rounds are shown in the magazine with one round loaded in the upper hoist tube. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the present invention is shown in FIG. 1. A roller chain 10 is driven by sprocket 12. Pawls 14a and 14b are attached at the ends of chain 10. Outboard rollers on chain 10 run in track 16. Support links 18a and 18b at each of pawls 14a and 14b respectively, provide support and slidably engage track 16. Cam arms 22a and 22b are in temporal contact with support links 18a and 18b. Further, support links 18a and 18b are fitted with a roller on the outboard end that is guided by chain track 16. Cam arms 22a and 22b are connected to adjustable rod 24a and 24b. Adjustable rods 24a and 24b are controlled by upper control cable mount 26a and 26b. Lower control cable mount 26a connects cam arm control cable 28a with pawl control arm 34a. Similarly, pawl control actuator 30 connects to cam arm control cable 28b and pawl control arm 34b. Pawl control arms 34a and 34b are flexibly connected by arm connection link 36. Restrainer section 38 prevents pawl control arm 34a from extending beyond a preset limit position. Pawls 14a and 14b include guide pins 40a and 40b. Further, pawls 14a and 14b include soft cushions or non-metallic tips 41a and 41b as shown. Hoist tube 42 is shown in which rounds are transferred to be supported and pushed by pawls 14a and 14b. 
     Referring now to FIG. 2, rounds R 1 , R 2  and R 3  are shown in loader structure 43. Round R 2  is transferred into hoist tube 42 where it is eccentrically positioned relative to pawls 14a and 14b. Round R 2  is transferred into hoist tube 42 through shutters 44a and 44b. Further, FIG. 2 shows cam control cables 28a and 28b. Sensors/receivers 52a and 52b are placed as shown to detect the presence of a round in hoist tube 42. Loader structure 43 forms the outer boundary of loader drum 54 where rounds are stored to be transferred. Also rounds in hoist tube 42 may be removed via access door 56. 
     The disclosure herein above relates to some of the most important structural features and operational parameters for the high cycle rate transfer device. The operation of the device under a best mode scenario is described herein below. 
     Typically, the present invention is coupled to an ammunition magazine drum from where rounds of ammunition are to be hoisted to an upper gun chamber. Accordingly, the high cycle rate transfer device accepts the round at a lower level and raises it up to the gun chamber. Similarly, ammunition or any other material could be hoisted from a lower level to a desired higher level using the device disclosed herein. 
     Referring now to FIG. 1, pawl 14a is shown in the up position and pawl 14b is shown in an extended position. In a retracted position pawls 14a and 14b stow into track 16 (shown in phantom lines). As pawl 14b moves up raising round R, pawl 14a will be retracted and stored into track 16 as it moves down, (similar to that shown on the phantom line for pawl 14b). Retraction of either pawl 14a or 14b is accomplished in exactly the same manner. For example the retraction of pawl 14a is accomplished by preventing the left end support link 18a from moving using cam arm 22a as the pawl is lowered. When pawl 14a and support link 18a are fully retracted, the left end of support link 18a is able to move past cam arm 22a in its extended position. In its fully retracted position guide pin 40a on pawl 14a is constrained in track 16 to prevent it from extending into hoist tube 42 before it reaches the bottom. 
     When pawl 14a reaches the bottom, guide pin 40a comes to rest in a contoured surface on the top of pawl control arm 34a. Both pawl control arms, 34a and 34b are pivoted simultaneously moving pawl 14a into position to raise round R and the opposite control arm into position to receive guide pin 40b on pawl 14b. One complete hoist cycle is thus completed and the hoist is ready to begin raising another round R using pawl 14a. 
     The two cam arms 22a and 22b, which are primarily used to retract pawl linkage at the top of hoist tube 42, are connected to pawl control arms 34a and 34b, via push/pull cables 28a and 28b. Accordingly, only a single hydraulic linear actuator, pawl control actuator 30, is required to position all the mechanisms controlling the relative positions of pawls 14a and 14b. During a round transfer cycle described herein above, when pawl 14a is all the way down and pin 40a is seated in pawl control arm 34a at restrainer section 38. Hydraulic pressure is applied to the upper end of actuator 30, and a spool moves downward overcoming a spring energized spool locking detent. Complete spool movement is detected by switches which sense whether a switch actuator block, attached to the top of the valve spool, is in either extreme position. The actuator spool remains in the down position until pawl 14a begins to raise and switches over to its original position at the end of the cycle by extending pawl control arm 34b. Chain 10 is used to raise and lower pawls 14a and 14b and is driven by a single rotary actuator on the axis of chain drive sprocket 12. 
     During a typical raise stroke, pawl support link 18a or 18b (depending upon which pawl is being raised) rotates downward (clockwise on 18a if pawl 14a is being raised) until it stops against the edge surface of the pawl being raised. This forms a rigid structure with which to push round R. 
     When a lower positioned pawl is extended to its ready to raise position, at the bottom, pawl support link 18a or 18b is maintained at 80° angle with pawl 14a or 14b, respectively. This design feature enables connection link 36 and associated linkage to retract pawl 14a or 14b and allow rounds of ammunition to be lowered back down from the transfer station into the loader outer structure 43. 
     Referring now to FIG. 2, rounds of ammunition referred to as R 1 , R 2 , and R 3  are placed into loader drum 54 by another mechanism (not shown). To hoist a round R, a mechanism inside loader drum 54 pushes the round in the direction shown through shutters 44a and 44b, and into hoist tube 42. Shutters 44a and 44b are cammed open by the round in the direction shown by the arrows and are spring-returned to their original position once the round is fully into hoist tube 42. Pawls 14a and 14b, which raise the round in hoist tube 42, are positioned below in order to urge the round upwards inside hoist tube 42. In other words, pawls 14a or 14b is located immediately below the round to be hoisted such that when the pawls are moved the round is pushed upwards inside hoist tube 42. As pawls 14a or 14b are pushed by chain 10 they move through a slot in the floor between track 16 and come in contact with the round to be hoisted. In the interest of simplicity, pawls 14a and 14b are not shown in FIG. 2. Once the round is in hoist tube 42, the round must be either hoisted or removed via access door 56. 
     in FIG. 2, the centerline of chain 10 and track 16 is offset from the center of hoist tube 42. This is primarily to avoid contact of pawls 14a and 14b with the primer. The primer is what initiates detonation and is centrally located at the bottom of the round. Further, pawls 14a and 14b include non-metallic tips 41a and 41b (refer to FIG. 1) which cushion the contact between the round being hoisted and the pawl in contact therewith. 
     Accordingly, the high cycle rate transfer device disclosed herein does not require a retraction cycle which requires both energy and time. Instead, the present invention provides a high cycle rate by allowing two pawls to consecutively move material without the need for a retraction cycle. In essence, the present invention provides a continuous transfer of material with a single drive and actuator. 
     While a preferred embodiment of the high cycle rate transfer device has been shown and described, it will be appreciated that various changes and modifications may be made therein without departing from the spirit of the invention as defined by the scope of the appended claims.