Patent Application
20220105595
The present invention relates generally to a separation system utilizing a traditional bolt and nut connective means for connecting at least two elements and an impact driver actuator to remove the nut or bolt to disconnect the elements.
Underwater vehicles, aircraft, launch vehicles and spacecraft have long required specialized separation systems for various situations. For example, aircraft require separation systems for the release of bombs or fuel tanks, launch vehicles require separation systems for separating rocket stages or payloads and spacecraft require separation systems for releasing solar arrays or antennas amongst other things.
Many separation systems have been utilized over the years but have had a variety of shortcomings. The paradox of separation devices is that they “Must Hold” and “Must Release” at different times. For example, pyrotechnic bolts have been utilized but have the shortcoming of not being testable prior to utilization as well as generating large shock forces upon separation and debris generation. Non-pyrotechnic separation nuts have also been utilized but, since the restraining nut in the system is split, the holding strength of the nut is less than a traditional nut and bolt connection. Various other systems (e.g. TiNi Frangibolt, TiNi shape memory actuators, burn wires, etc.) have been utilized with some success but all suffer from relatively weak load capability when compared to a traditional bolt and nut connection.
Structural engineers consider a bolt and nut connection a pure structural element much like a riveted joint or a welded joint. A bolt and nut connection is well understood and considered the utmost in reliability if the proper bolt and nut are used for the connection as well as tensioned under the proper torque values. A bolt and nut connection is also capable of disconnection by simply unscrewing the nut from the bolt or vice versa.
Utilization of a bolt and nut connection would be highly desirable for all separation systems but standard removal of the bolt or nut to accomplish separation using traditional actuators (e.g. electric motors) has heretofore been impractical since the torque required to unscrew the bolt or nut would require an extremely large motor (e.g. electric, pneumatic or hydraulic) to overcome the starting torque of the bolt or nut.
Impact drivers were invented in the 1930's to provide compact sources of torque for bolt/nut removal, see U.S. Pat. No. 2,012,916 Pott. The advent of battery powered handheld electric power tools, see U.S. Pat. No. 6,598,684 Watanabe, has driven development of compact, low mass high torque impact drivers. For example, a brushless electric motor with a 160:1 gear ratio harmonic drive can provide on the order of 40 inch-lbs of torque. When an impact driver head with a brushless motor is utilized which is of the same volume and mass as the exemplar harmonic drive motor, an instantaneous torque of 1600 in-lbs is readily produced. This is 40 times the torque for the same mass and volume actuator and makes removal of highly tightened bolts and nuts possible with a handheld battery powered tool.
The disclosed subject matter helps to avoid these and other problems.
The present invention relates generally to a separation system utilizing a traditional bolt and nut connective means for connecting at least two elements and an impact driver actuator to remove the nut or bolt to disconnect the elements.
The inventive system utilizes a traditional bolt and nut combination as the primary structural element (the “Must Hold” state) to hold together at least two elements and an impact actuator to remove either the bolt or the nut to permit separation (the “Must Release” state) of at least two elements. The bolted joint can consist of one or more bolt and nut combinations (with washers, lock washers, locknuts, etc.)
An impact actuator is collocated with each bolt and nut combination and can apply torque to either the bolt or nut to separate at least two elements.
Additionally, an impact actuator can be located on a form of trolley or robotic arm that can move the actuator to each bolt and nut location and can apply torque to either the bolt or nut to separate at least two elements.
The impact actuator is preferably electrically actuated via a brushless motor capable of operating in a low or zero pressure environment but can be of any motive power deemed convenient for the application (e.g. brushed electric motor, pneumatic motor, hydraulic motor, etc.).
The component driven by the impact actuator can be either a bolt (or screw which, the term “bolt” from here forward in this specification will mean either bolt or screw) or nut (or both bolt and nut) via a socket head, a driven bolt directly connected to the impact actuator, a nut via a socket head or a driven nut directly connected to the impact actuator.
The main advantage of using the invention is the provision of a novel means of utilizing an impact driver actuator mechanism located at each nut and bolt connection that permits utilization of the full strength of each nut and bolt connection while permitting release of said nut and bolt connection at any desired time.
Utilization of the combination of a bolt and nut connection combined with an impact actuator in a separation system provides the following advantages: 1. The maximum strength of the bolted joint can be utilized, 2. The system may be tested for “Must Hold” and “Must Release” states any number of times, 3. Operational separation of “Must Hold” and “Must Release” state risk sources, 4. Utilization of the holding torque of the impact actuator to prevent backing off (i.e. loosening) of the nut or bolt under any circumstances. 5. Automatic impact actuator motor over torque protection provided by the inherent impact actuator clutch action. 6. High holding strength density of the releasable assembly actuator (i.e. mass to volume ratio divided by the holding strength of the system).
Some applications of the separation system include submarine torpedo release mechanisms, submarine door release mechanisms, and underwater cable release mechanisms. Some aircraft applications are bomb release mechanisms, fuel tank release mechanisms, landing gear release mechanisms, and aircraft door release mechanisms. Some launch vehicle applications include rocket stage separation systems, payload separation systems and landing gear release mechanisms. Some spacecraft applications include solar array release mechanisms and antenna release mechanisms amongst other things.
A more complete understanding of the invention and the many attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawings wherein:
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Impact actuator 104 is preferably electrically actuated via a brushless motor capable of operating in a liquid, high pressure, low or zero pressure (vacuum) environment but can be of any motive power deemed convenient for the application (e.g. brushed electric motor, pneumatic motor, hydraulic motor, etc.). The motor may also consist of a redundant motor system (two or more motors connected in series or parallel) to provide increased reliability for the assured separation (the “Must Release” state) of at least two elements 102 and 103. Additional operational redundancy may also occur if, for example, two impact actuators 104 are utilized with a trolley 500 or two impact actuators 104 are utilized with two robotic arms 501.
Operation of traditional impact actuator mechanisms 104, such as those described in U.S. Pat. No. 2,256,496 Robinson possesses a unique automatic driving motor over-torque protection function. In the event the torque required to release the driven element is above the direct shaft torque provided by the driving motor, a clutch mechanism permits the impact hammer to slide past the anvil at a torque value below the motor stalling torque, thus providing motor over-torque protection and preventing damage to the driving motor.
The inventive device permits the maximum strength of the bolted joint (bolt 100 and nut 101) to be utilized thus utilizing the minimum number of fasteners required to hold elements 102 and 103 together. This has the effect of minimizing the total mass required for the holding/release mechanism of the overall system.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
The present application claims priority from U.S. Provisional Patent Application Ser. No. 63/087,250, filed on Oct. 4, 2020, which is incorporated herein by its entirety and referenced thereto.
| Number | Date | Country | |
|---|---|---|---|
| 63087250 | Oct 2020 | US |
