Patent Grant
8624172
Conventional projectiles, such as bombs or missiles, have movable fins which help to steer the projectiles toward a particular target. In certain situations, such as prior to launch or during transportation, a locking mechanism holds the fins in a zero angle of attack position relative to the projectile's centerline. Such locking minimizes wear, overstressing, and the possibility of damage to the fins and associated steering systems. Additionally, the locking mechanism allows for release of the fins at the time of use so that the fins can be driven to computer controlled positions.
Conventional locking mechanisms can be transitioned from a locked state to an unlocked state in a variety of ways. For example, the locking mechanism can be configured as an explosive release mechanism having an explosive squib. The explosive squib can include a small tube that contains an explosive substance and a detonator disposed along a length of the tube. Initially, the explosive squib holds a release mechanism against the fins of the guided munitions to maintain the fins in an aligned or non-deployed position. When the detonator receives an electric discharge signal, the detonator detonates the explosive squib to release the lock mechanism. With such a release, the lock mechanism allows the fins to move from the non-deployed or locked position to a deployed position. Other conventional locking mechanisms include brakes, solenoids, and fin lock release motors configured to hold the fins in a retracted or stationary state and release the fins to allow the fins to move to a deployed position.
In addition to the locking mechanism, conventional projectiles can also include a driving mechanism to adjust the position of the fins during operation. For example, certain projectiles include a Control Actuation System (CAS) having an actuator, such as a motor, and an electronic controller, such as a flight computer. In use, the actuator is configured to adjust the position of the fins in response to steering commands received from the controller to steer the projectile along a flight path toward a target.
As indicated above, certain conventional projectiles include both a locking mechanism and a driving mechanism to control operation of the projectile fins. With such a configuration, the use of conventional locking mechanisms can affect the overall cost, weight, and reliability associated with the projectiles.
For example, the locking mechanism can be configured as an explosive release mechanism. While conventional explosive release mechanisms have a minimal effect on the overall weight of a projectile, the explosive release mechanisms are one-time use devices that do not allow for resettability without incurring a relatively high replacement cost. Also, explosive devices have a reliability rating, thereby impacting the overall reliability of the projectile.
While other conventional locking mechanisms such as brakes, solenoids, and fin lock release motors are resettable, these locking mechanisms add to the cost and weight a projectile when taken in conjunction with the projectile's driving mechanism. Furthermore, one of these locking mechanisms can be added to a projectile as a distinct mechanical component, separate from the driving mechanism. The addition of a separate mechanical assembly can reduce the overall reliability and increase weight, power draw, and cost of the projectile with respect to the projectile's operation.
By contrast to conventional locking mechanisms, embodiments of the present invention relate to a shift lock assembly for each of projectile's fins. In one arrangement, a drive motor is configured to operate the shift lock assembly to unlock drive shaft that secures a set of projectile fins. Once disposed in an unlocked position, the same drive motor is further configured to operate the shift lock assembly to cause and the drive shaft to drive the projectile fins to commanded positions. The use of the shift lock assembly reduces the costs experienced with conventional locking mechanisms. For example, motors, electromechanically brakes, solenoids, and explosive devices found in conventional locking mechanisms are typically more expensive to procure and install compared to the shift lock assembly. Additionally, shift lock assembly weighs less than the motors and brakes found in conventional locking mechanisms. Accordingly use of the shift lock assembly can reduce the overall weight of the projectile, compared to conventional locking mechanisms. Furthermore, because the shift lock assembly adds relatively few mechanical components to the projectile, the reliability of the shift lock assembly is relatively higher than conventional locking mechanisms such as motors, solenoids, and explosive devices and their related drive electronics.
In one arrangement, a shift lock assembly includes a drive member carried by a drive shaft and configured to rotatably couple to a drive motor and a shift mechanism disposed between the drive member and a ground plate, the shift mechanism configured to move between a first position and a second position relative to the drive member and the ground plate. When disposed in the first position, the shift mechanism is configured to couple the drive shaft to the ground plate and decouple the drive shaft from the drive member to allow rotation of the drive member relative to the drive shaft. When disposed in the second position, the shift mechanism is configured to couple the drive shaft to the drive member and decouple the drive shaft from the ground plate to allow rotation of the drive shaft in response to rotation of the drive member.
The foregoing and other objects, features and advantages will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention.
Embodiments of the present invention relate to a shift lock assembly for each projectile fin. In one arrangement, a single drive motor is configured to operate the shift lock assembly to unlock a drive shaft that secures each projectile fin. Once disposed in an unlocked position, the drive motor is further configured to operate the shift lock assembly to cause and the drive shaft to drive the projectile's fin to a commanded position. The use of the shift lock assembly reduces the costs experienced with conventional locking mechanisms. For example, motors, electromechanically brakes, solenoids, and explosive devices found in conventional locking mechanisms are typically more expensive to procure and install compared to the shift lock assembly. Additionally, shift lock assembly weighs less than the motors and brakes found in conventional locking mechanisms. Accordingly use of the shift lock assembly can reduce the overall weight of the projectile, compared to conventional locking mechanisms. Furthermore, because the shift lock assembly adds relatively few mechanical components to the projectile, the reliability of the shift lock assembly is relatively higher than conventional locking mechanisms such as motors, solenoids, and explosive devices and their related drive electronics.
The motor 12 is configured to mechanically couple to the shift lock assembly 16 to both unlock the drive shaft 14 from a locked position and to drive the drive shaft 14 to position the output shaft 26. For example, the motor 12 is disposed in electrical communication with a controller 36, such as a processor and memory, which receives load positioning signals 37 from a flight control center 38. While the flight control center 38 can provide the signals 37 in a variety of ways, in one arrangement, the flight control center 38 provides the signals 37 from a remote location. Based upon the signals 37 received by the controller 36, the controller 36 commands the motor 12 to adjust the position of the drive shaft 14, via the shift lock assembly 16, to move the load 26 to a desired position. For example, when used as part of a projectile, such as a missile, the controller 36 commands the motor 12 to adjust the position of the fins through the output shaft 26 to steer the projectile towards a target.
As shown in
In one arrangement, the drive member 40 is configured to rotatably couple to the drive motor 12. For example, the drive mechanism 40 is configured as a gear having teeth that mesh with the corresponding teeth of a gear 50 carried by the motor 12. As the gear 50 of the motor 12 rotates in a counterclockwise direction, the drive member 40, in response, rotates in a clockwise direction. The drive member 40 is configured to operate in conjunction with the shift mechanism 42, as will be described below, to unlock the drive shaft 14 from a locked state and to drive the drive shaft 14 and corresponding output shaft 26 to a commanded position.
The shift mechanism 42 configured to move between a first position and a second position relative to the drive member 40 and the ground plate 44 to selectively couple the drive shaft drive mechanism 46 to one of the ground plate 44 and the drive member 40. For example, the shift mechanism 42 includes a spring 48 disposed between the shift mechanism 42 and a portion of the drive shaft drive mechanism 46 as well as the ground plate 44. As will be described above, expansion of the spring 48 from a compressed state, as shown in
As indicated above, the drive shaft drive mechanism 46 is coupled to the drive shaft 14 at the first end 18. While the drive shaft drive mechanism 46 can be coupled to the drive shaft 14 in a variety of ways, in one arrangement, the drive shaft drive mechanism 46 is splined and fastened, such as via a bolt, to the drive shaft 14. Furthermore, the shift mechanism 42 is moveably coupled to the drive shaft drive mechanism 46. For example, as shown in
With such positioning, the face 62 of the drive member 40 pushes against the drive member mating portion 60, thereby causing a ring 64 of the shift mechanism 42 to compress the spring 48 against the drive shaft drive mechanism 46. Furthermore, with the ground plate mating portion 58 disposed within the ground plate mating portion 58 and the mating support 54 disposed within the slot 52 of the drive shaft drive mechanism 46, and with reference to
In a subsequent state, as illustrated in
For example, in the case where an operator wants to unlock the drive shaft 14, with reference to
With the mating opening 68 aligned with the drive member mating portion 60, the spring 48 expands along the longitudinal axis 30 of the drive shaft 14, as indicated in
As indicate above, the use of the shift ring assembly 16 allows a single motor 12 to drive both an drive shaft locking mechanism and an output shaft positioning mechanism. Accordingly, use of the shift lock assembly reduces the costs experienced with conventional locking mechanisms and reduces the overall weight of the projectile, compared to conventional locking mechanisms.
While various embodiments of the invention have been particularly shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
For example, as indicated above, the shift ring assembly 16 is disposed at a first end 18 of the drive shaft 14. Such indication is by way of example only. In one arrangement, the shift lock assembly 16 can be placed at any location relative to the drive motor 12 to properly balance inertia, backlash, and loads.
As indicated above, the shift ring assembly 16 is utilized to both lock and allow positioning of projectile fins in a projectile. Such indication is by way of example only. The shift lock assembly 16 can be applied to any mechanical system that requires a load to be locked into a position, such as for transportation and storage, and then shifted into an operational state where a motor can drive it to a commanded position using only the motor power that drives the load.
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