Patent Application
20170146328
Field
The present invention relates generally to very low-power actuation devices and more particularly to very low-power actuation devices for guided gun-fired munitions and mortars that can be scaled to any caliber munitions, including medium and small caliber munitions.
Prior Art
Since the introduction of 155 mm guided artillery projectiles in the 1980's, numerous methods and devices have been developed for actuation of control surfaces for guidance and control of subsonic and supersonic gun launched projectiles. The majority of these devices have been developed based on missile and aircraft technologies, which are in many cases difficult or impractical to implement on gun-fired projectiles and mortars. This is particularly true in the case of actuation devices, where electric motors of various types, including various electric motor designs with or without gearing, voice coil motors or solenoid type actuation devices, have dominated the guidance and control of most guided weaponry.
Unlike missiles, all gun-fired and mortar projectiles are provided with initial kinetic energy through the pressurized gasses inside the barrel and are provided with flight stability through spinning and/or fins. As a result, they do not require in-flight control action for stability and if not provided with trajectory altering control actions, such as those provided with control surfaces or thrusters, they would simply follow a ballistic trajectory. This is still true if other means such as electromagnetic forces are used to accelerate the projectile during the launch or if the projectile is equipped with range extending rockets. As a result, unlike missiles, control inputs for guidance and control is required only later during the flight as the projectile approaches the target.
In recent years, alternative methods of actuation for flight trajectory correction have been explored, some using smart (active) materials such as piezoelectric ceramics, active polymers, electrostrictive materials, magnetostrictive materials or shape memory alloys, and others using various devices developed based on micro-electro-mechanical (MEMS) and fluidics technologies. In general, the available smart (active) materials such as piezoelectric ceramics, electrostrictive materials and magnetostrictive materials (including various inch-worm designs and ultrasound type motors) need to increase their strain capability by at least an order of magnitude to become potential candidates for actuator applications for guidance and control, particularly for gun-fired munitions and mortars. In addition, even if the strain rate problems of currently available active materials are solved, their application to gun-fired projectiles and mortars will be very limited due to their very high electrical energy requirements and the volume of the required electrical and electronics gear. Shape memory alloys have good strain characteristics but their dynamic response characteristics (bandwidth) and constitutive behaviour need significant improvement before becoming a viable candidate for actuation devices in general and for munitions in particular.
The currently available actuation devices based on electrical motors of various types, including electrical motors, voice coil motors and solenoids, with or without different gearing or other mechanical mechanisms that are used to amplify motion or force (torque), and the aforementioned recently developed novel methods and devices (based on active materials, such as piezoelectric elements, including various inch-worm type and ultrasound type motors), or those known to be under development for guidance and control of airborne vehicles, such as missiles, have not been shown to be suitable for gun-fired projectiles and mortars. This has generally been the case since almost all available actuation devices that are being used or are considered for use for the actuation of control surfaces suffer from one or more of the following major shortcomings for application in gun-fired projectiles and mortars:
Three classes of actuation devices are disclosed herein. The first class of actuation devices provide a nearly continuous actuation motion to the intended control surface. The second class of actuation devices are for applications in which bang-bang control strategy is warranted, such as for munitions with very short flight time or for applications in which the actuation devices with a limited number of actuation actions are used mainly for so-called terminal guidance to the target, i.e., during the last few seconds of flight. The third class corresponds to actuation devices that are used for direct tilting of the projectile nose and which are particularly suitable for small and medium caliber guided munitions.
Such actuators have the following basic characteristics:
The aforementioned actuator devices disclosed herein provide very low power, low cost, and highly effective solution options for the full range of gun-fired and mortar munitions, including medium and small caliber munitions.
A need therefore exists for low-cost actuator devices that address the aforementioned limitations of currently available control surface actuation devices in a manner that leaves sufficient volume inside munitions for sensors, guidance and control, and communications electronics and fusing, as well as the explosive payload to satisfy the lethality requirements of the munitions.
Such control surface actuation devices must consider the relatively short flight duration for most gun-fired projectiles and mortar rounds, which leaves a very short period of time within which trajectory correction/modification has to be executed. This means that such actuation devices must provide relatively large forces/torques and have very high dynamic response characteristics (“bandwidth”).
The control surface actuation device applications may be divided into two relatively distinct categories. Firstly, control surface actuation devices for munitions with relatively long flight time and in which the guidance and control action is required over relatively longer time periods. These include munitions in which trajectory correction/modification maneuvers are performed during a considerable amount of flight time as well as within a relatively short distance from the target, i.e., for terminal guidance. In many such applications, a more or less continuous control surface actuation may be required. Secondly, control surface actuation devices for munitions in which the guidance and control action is required only within a relatively short distance to the target, i.e., only for terminal guidance purposes.
Such actuation devices must also consider problems related to hardening of their various components for survivability at high firing accelerations and the harsh firing environment. Reliability is also of much concern since the rounds need to have a shelf life of up to 20 years and could generally be stored at temperatures in the range of −65 to 165 degrees F.
In addition, for years, munitions developers have struggled with the placement of components, such as sensors, processors, actuation devices, communications elements and the like within a munitions housing and providing physical interconnections between such components. This task has become even more difficult with the increasing requirement of making gun-fired munitions and mortars smarter and capable of being guided to their stationary and moving targets. It is, therefore, extremely important for all guidance and control actuation devices, their electronics and power sources not to significantly add to the existing problems of integration into the limited projectile volume.
The three classes of control surface actuation devices can be used for actuation of various types of control surfaces, whether they require rotary or linear actuation motions, such as fins and canards or the like. Two classes of the actuation devices disclosed herein are particularly suited for providing high force/torque at high speeds for bang-bang feedback guidance and control of munitions with a very high dynamic response characteristic. As a result, the guidance and control system of a projectile equipped with such control surface actuation devices is capable of achieving significantly enhanced precision for both stationary and moving targets.
The actuator devices disclosed herein occupy minimal volume since they are powered by the detonation of gas generating charges to generate pressurized gas for pneumatic operation of the actuating devices (the first class of actuation devices) or by detonation of a number of gas generating charges embedded in the actuation device “cylinders” to provide for the desired number of control surface actuation (the second class of actuation devices). As a result, the second class of control surface actuation devices can provide a limited number (e.g., 20-50) of control surface actuations, but with actuating forces/torques of order of magnitude larger than those possible by current electrical and pneumatic systems. With such control surface actuation technology, since solid gas generating charges have energy densities that are orders of magnitude higher than the best available batteries, a significant total volume savings is also obtained by the elimination of batteries that are required to power electrically powered actuation devices. It is also noted that the gas generating charges of the actuator devices disclosed herein are intended to be electrically initiated, but such initiation devices utilize less than 3 mJ of electrical energy (other electrical initiators that utilize only tens of micro-J of energy can also be used). The first class of actuation devices also require electrical energy for the operation of their pneumatic valves, but such small solenoid operated valves are also available that require small amounts of energy to operate, such as around 3 mJ.
The control surface actuation devices disclosed herein are also capable of being embedded into the structure of the projectile, mostly as load bearing structural components, thereby occupying minimal projectile volume. In addition, such actuation devices and their related components are better protected against high firing acceleration loads, vibration, impact loading, repeated loading and acceleration and deceleration cycles that can be experienced during transportation and loading operations.
Three classes of control surface actuation devices, their basic characteristics, modes of operation, and method of manufacture and integration into the structure of projectiles are described below. Such control surface actuation devices can provide very low power, very low cost, high actuation force/torque and fast response (high dynamic response) actuation devices that occupy very small useful projectile volume. Furthermore, such control surface actuation devices can readily be scaled to any munitions application, including medium to small caliber munitions. In addition, due to their basic design and since they can be integrated into the structure of munitions as load bearing elements, they can be designed to withstand very high-G firing setback accelerations of well over 50 KG. The actuation devices disclosed herein can also be configured as modular units and thereby provide the basis for developing common actuation solutions to a wide range of gun-fired projectiles and mortars for actuating control surfaces. munition comprising:
Accordingly, a munition is provided. The munitions comprising: a control surface actuation device comprising: an actuator comprising two or more pistons, each of the pistons being movable between an extended and retracted position, the retracted position resulting from an activation of each of the two or more pistons; and a movable rack having a portion engageable with a portion of the two or more pistons to sequentially move the rack upon activation of each of the two or more pistons; and a control surface operatively connected to the rack such that movement of the rack moves the control surface.
The actuator can comprise three pistons.
The actuator can comprise: a housing for movably housing each of the two or more pistons; a plurality of gas generation charges generating a gas in fluid communication with the housing; and an exhaust port for exhausting gas from the housing generated by the plurality of gas generation charges; wherein activation of each of the plurality of gas generation charges results in an increase in pressure in the housing causing the piston to move in the housing from the retracted to the extended position. The actuator can further comprise a gas reservoir, wherein the plurality of gas generation charges are disposed in the gas reservoir, the gas reservoir being in fluid communication with the housing. The actuator can further comprise a valve for directing gas generated in the reservoir to a respective housing. The plurality of gas generation charges can be disposed in the housing. The actuator further can comprise a return spring for biasing each of the two or more pistons in the retracted position.
The portion of the rack can be a plurality of spaced portions and the portion of the piston is an end portion of the piston exposed when the piston is in the extended position. The plurality of spaced portions on the rack can be one of convex or concave portions and the end portion is the other of the convex or concave portions. The convex and concave portions can be conical.
The movable rack can be linear and move linearly. The movable rack can be curved and move around a central axis. The movable rack can rotate.
The control surface can be one or more canards.
The munition can further comprise a casing, wherein the actuator is integral with a structure of the casing.
The rack can be operatively connected to the control surface by a mechanism to convert movement of the rack to a corresponding movement of the control surface. The mechanism can be a pinion.
The rack can be operatively connected to the control surface directly wherein movement of the rack directly corresponds to movement of the control surface.
The housing can be a cylinder.
Also provided is a munition comprising: a casing having a first portion and the second portion; an actuator comprising two or more pistons, each of the pistons being connected at a first end to the first portion of the casing and engaged at a second end to the second portion of the casing, each of the pistons being capable of having an extended and retracted position relative to the first and second ends, the retracted position resulting from an activation of each of the two or more pistons; wherein activation of one or more of the two or more pistons moves the first portion relative to the second portion.
The first portion can be a cylindrical portion of the casing and the second portion can be a nose portion of the casing.
The engagement at the second end can be a rotatable connection.
The nose portion can be rotatably connected to the cylindrical portion and the engagement at the second end can be a contact of the second end with the nose portion.
The connection at the first end can comprise the two or more pistons being housed in a housing associated with the first portion. The housing can be integral with the first portion.
Still further provided is an actuator comprising: a housing; a piston movably disposed in the housing, the piston being movable between an extended and retracted position; a plurality of gas generation charges generating a gas in fluid communication with the housing; and an exhaust port for exhausting gas from the cylinder generated by the plurality of gas generation charges; wherein activation of each of the plurality of gas generation charges results in an increase in pressure in the housing causing the piston to move in the housing from the retracted to the extended position.
The actuator can further comprise a return spring for biasing the piston in the retracted position.
The plurality of gas generation charges can be disposed in the housing.
These and other features, aspects, and advantages of the apparatus and methods of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:
A known miniature inertial igniter 100 is shown in
A “mechanical stepper motor” that operates pneumatically, and can apply large actuation forces/torques has also been developed, as shown in U.S. Pat. No. 8,110,785, the disclosure of which is incorporated herein by reference. Such actuation devices use very small electrical energy for their operation. The operation of this novel class of mechanical stepper motor type actuators is based on the principles of operation of simple Verniers. They use pneumatically actuated three or more pistons to achieve step-wise linear or rotary motion of the actuation device. A cutaway view of a pneumatic linear type of such an actuator 200 is shown in
A lanyard-driven electrical power generator has also been developed for gravity dropped weapons that can overcome a number of shortcomings of the currently available devices such as problems with very high and very low altitude drops, while providing drop and a number of other event detection capabilities used for “safe” and “arm” (S&A) functionalities. Such lanyard-driven electrical power generator is disclosed in U.S. patent application Ser. No. 12/983,301, the disclosure of which is incorporated herein by reference. As shown in
To provide for safety, when the weapon is mounted on the aircraft, there is no energy stored in a spiral power spring 310, and the shaft of the generator 306 is locked in position, through a flywheel 312, preventing any power generation. When the weapon is released, the lanyard 302 unwinds from the input drum 304, winding and storing energy in the power spring 310. When the lanyard 302 has uncoiled a predetermined length, the lanyard breaks away from the aircraft and descends with the weapon. Just before the lanyard breaks-away, it actuates the locking mechanism which was heretofore holding the flywheel 312 and rotor of the generator 306 stationary, and the power spring 310 transfers its stored mechanical potential energy to the generator (as input rotation) 306. A ratchet mechanism 314 on the cable drum 304 prevents reaction-motion of the cable drum 304, and a one-way clutch 316 allows the flywheel 312 and generator 306 to spin freely after the power spring 310 has unwound completely.
The dynamo-type generator of
Turning now to control surface actuator devices in detail. Two classes of such actuation devices are first discussed. The first class of actuation devices would provide a nearly continuous actuation motion to the intended control surface. The second class of actuation devices are intended for applications in which bang-bang control strategy is warranted, such as for munitions with very short flight time or for applications in which the actuation devices with a limited number of actuation actions are used mainly for the so-called terminal guidance to the target, i.e., during the last few seconds of the flight. The third class corresponds to the actuation devices that provide a limited number of actuation actions and are used to tilt the projectile nose and which are particularly suitable for small and medium caliber guided munitions.
Structurally Integrated Control Surface Actuators with Limited Actuation Actions
The control surface actuator devices discussed with regard to
The canard actuation device 400 is based on the aforementioned mechanical stepper motor design discussed above with regard to
It is noted that the aforementioned charges can be initiated electrically by a guidance and control system. Assuming that the canards 402 operate at an upper speed of 20-30 steps per seconds each, for a nominal required initiation electrical energy of 3 mJ, the required electrical energy per second for both canards 402 working at the same time will be 120-180 mJ, i.e., a power requirement of 120-180 mW. Development of electrical initiators that require at most 50 micro-J and are extremely fast acting, would further reduce the required electrical energy to a maximum of 2-3 mJ.
The control surface actuator devices discussed with regard to
Similarly to the canard actuator of
The control surface actuator discussed with regard to
The control surface actuator 600 discussed with regard to
Specifically, an actuator body 602 having cylinders 604 for holding the piston actuators (not shown) is provided on an aft end of the projectile body 606 for each of the canard pairs 402. Each of the canard pairs 402 are rotatable and include at least a partial disc 608 having pockets 406a. The pistons (not shown) include the tip portion 416 that is extendable into the pockets 406a upon activation of the piston or retractable therefrom by a return spring 414. In this way, the disc 608 can be moved incrementally to directly turn the canards 402.
Additionally, this particular embodiment of the 2-piston design employs transverse pistons as opposed to the axially positioned pistons previously discussed. This piston arrangement allows for the elimination of the pinion gearing, and may have advantages over the axial piston arrangement with respect to possible setback/setfoward effects on the pistons. Such a transverse piston arrangement could also be implemented on other previously described designs.
The control surface actuator discussed with regard to
Such control surface actuation device as implemented in small or medium caliber munitions is shown in
The control surface actuation device has very high dynamic response characteristics, since it is based on detonations of charges and utilization of the generated high detonation pressures to drive the actuation devices. For example, such a linear control surface actuator operating at a detonation pressure of around 5,000 psi and with a pressure surface of only 0.2 square inches (0.5 inch dia.) would readily provide a force of around 980 lbs or 4,270 N (which can still be significantly magnified via the inclined contact surfaces between the piston and the translating element of the actuator). A rotary actuator with a similar sized pressure area with an effective diameter of 2 inches and operating at 5000 psi could readily produce a torque of over 100 N-m. In addition, reliable detonation within time periods of 1-2 msec and even significantly lower with the aforementioned micro-J initiation devices (being developed jointly with ARL) should be achievable. Thereby, the peak force/torque should be achievable within 1-2 msec or less, providing control surface actuation devices with very high dynamic response characteristics that are ideal for guidance and control of precision gun-fired projectiles of different calibers and mortars.
The mechanical stepper motors and actuators disclosed above actuate by detonating gas charges, and as such, have the capability of generating large actuation forces. Consequently, such mechanical stepper motors will have widespread commercial use in emergency situations that may require a large generated force and where a one-time use may be tolerated. For Example, the mechanical stepper motors and actuators disclosed above can be configured to pry open a car door after an accident to free a trapped passenger or pry open a locked door during a fire to free a trapped occupant.
The novel mechanical stepper motors and actuators disclosed above, being actuated by detonating gas charges, do not require an external power source for actuation, such as hydraulic pumps or air compressors. Accordingly, such mechanical stepper motors can be adapted for use in remote locations where providing external power to the device is troublesome or impossible. For Example, the novel mechanical stepper motors disclosed above can be used under water, such as at the sea floor.
The novel mechanical stepper motors and actuators disclosed above, due to their capability of generating large actuation forces, can also be used for heavy duty industrial applications, such as for opening and closing large valves, pipes, nuts/bolts and the like.
As technology advances and buildings grow taller, oil exploration gets deeper, vehicles get larger and faster and the frontiers of ocean and space expand, the need for emergency, remote and heavy use actuators will grow. The mechanical stepper motors and actuators disclosed above will be vital to the continued advancement of such technologies and continued expansion of such frontiers. Growth in these areas can stagnate or reverse if there is no practical answer to saving people trapped in a vehicle traveling at great speeds, saving people trapped on the 100th floor of a skyscraper, plugging a leak on an oil pipeline 1 mile deep on a sea floor, turning on a large valve at a damaged nuclear power plant or providing the actuators necessary for the colonization of space. For at least these reasons, emergency, heavy and remote actuation devices are expected to be actively pursued for decades. The use of the mechanical stepper motors and actuators disclosed above could provide such improvements.
While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.
This application is a Continuation Application of U.S. application Ser. No. 14/975,823, filed on Dec. 20, 2015, which is a Divisional Application of U.S. application Ser. No. 13/542,635, filed on Jul. 5, 2012, which claims the benefit of U.S. Provisional Application No. 61/504,304 filed on Jul. 4, 2011, the entire contents of each of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61504304 | Jul 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13542635 | Jul 2012 | US |
| Child | 14975823 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14975823 | Dec 2015 | US |
| Child | 15403008 | US |
