US20050056509A1

US20050056509A1 - Shock isolation system

Info

Publication number: US20050056509A1
Application number: US10/663,274
Authority: US
Inventors: Ben Ishino
Original assignee: Boeing Co
Current assignee: Boeing Co
Priority date: 2003-09-16
Filing date: 2003-09-16
Publication date: 2005-03-17

Abstract

A shock isolation system for reducing the transmission of shocks between first and second devices is provided. The system includes linear bearings assemblies that extend substantially parallel in an axial direction between the first and second devices. Each bearing assembly has a shaft member that is connected to one of the devices and a linear bearing connected to the other of the devices. The linear bearings move axially on the shafts to accommodate relative motion between the devices in the axial direction while restraining rotation therebetween about an axis of the devices. The system also includes isolators that are axially loaded by a relative motion between the devices. The isolators are thereby deformed and reduce the transmission of energy between the devices.

Description

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under contract number HQ0006-01-C-0001 awarded by the U.S. Office of the Secretary of Defense Ballistic Missile Defense. The government has certain rights in this invention.

BACKGROUND OF THE INVENTION

1) Field of the Invention
The present invention relates to shock isolation and, more particularly, to a system for reducing the transmission of energy in the form of shocks, including vibrations, between devices while maintaining angular orientation of the devices.
2) Description of Related Art
A typical aerospace vehicle in a missile defense system includes a kill vehicle that is releasably connected to a boost device. The boost device provides thrust for launching the kill vehicle and directing the vehicle towards a target, such as a missile in flight. At a predetermined stage of flight, such as upon completion of the combustion of the fuel in the boost device, the kill vehicle and the boost device separate and the kill vehicle continues toward the target. Prior to separation, the boost device can communicate guidance information to the kill vehicle, including current location, orientation, and velocity information for the boost device. The kill vehicle also has a guidance system that controls the flight of the kill vehicle toward the target, based in part on the guidance information received from the boost vehicle.
While the boost device and kill vehicle are connected, the boost device can provide significant thrust to the kill vehicle, and shock motion associated with the thrust can damage equipment in the kill vehicle such as electronics in guidance or other avionic devices. Elastomeric isolators are conventionally used for reducing the transmission of shocks, including vibrations, but the use of isolators for connecting the boost device and kill vehicle can allow undesirable or unacceptable rotational motion therebetween, i.e., about a longitudinal or roll axis that extends through the boost device and kill vehicle. This relative motion between the boost device and kill vehicle can complicate the determination of the guidance of the kill vehicle because the guidance information determined by the boost vehicle may not directly correspond to that of the kill vehicle. For example, the guidance information communicated by the boost device before separation may not accurately describe the orientation of the kill vehicle if the kill vehicle is rotated about the roll axis relative to the boost device. However, if isolators are not used, the electronic equipment in the kill vehicle must be designed to withstand the shocks associated with the boost device. This generally increases the cost and weight of the electronic equipment.
Thus, there exists a need for an improved system for reducing the transmission of shocks, including vibrations, between devices while maintaining the relative rotational orientation of the devices. Preferably, the system should be compatible with an aerospace vehicle in which a boost device generates significant and/or repetitive shocks.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a shock isolation system for reducing a transmission of energy in the form of shocks between first and second devices, such as a boost device and a kill vehicle of an aerospace vehicle. The system includes at least two linear bearing assemblies that extend parallel in an axial direction between the first and second devices. Each bearing assembly has a shaft member connected to one of the first and second devices and a linear bearing connected to the other of the devices. The linear bearings are configured to adjust, i.e., move, axially on the shafts so that the first and second devices are configured for relative motion therebetween in the axial direction and the bearing assemblies restrain a rotation between the first and second devices about an axis defining the axial direction. The system also includes at least two isolators configured to be axially loaded by a relative motion between the first and second devices in the axial direction. At least one of the isolators is deformed by the relative axial motion to at least partially reduce the transmission of energy between the devices. Further, the centers of gravity of the devices can be positioned outside a plane defined by the isolators, and the linear bearing assemblies can be configured for independent axial adjustment, i.e., movement, so that the first device can rotate relative to the second device about an axis transverse to the axial direction.
According to one aspect of the invention, the linear bearing assemblies and isolators are arranged in a substantially planar and polygonal configuration. Each linear bearing can extend circumferentially around the shaft and can have a plurality of balls for rollably contacting the shaft. The isolators, which can be formed of rubber, elastically deformable polymers, or springs, can be positioned on opposite sides of the linear bearings and also can extend circumferentially around the shafts. Alternatively, each isolator can extend between the first and second devices separately from the bearing assemblies.
Thus, the shock isolation system of the present invention reduces the transmission of energy between the devices while maintaining the rotational orientation therebetween.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
FIG. 1 is a perspective view illustrating an isolation system disposed between a boost device and a kill vehicle according to one embodiment of the present invention;
FIG. 2 is an elevation view illustrating one of the bearing assemblies with two isolators of the isolation system of FIG. 1;
FIG. 3 is a section view in elevation illustrating the bearing assembly and isolators of FIG. 2;
FIG. 4 is an elevation view schematically illustrating an isolation system according to another embodiment of the present invention; and
FIG. 5 is a section view as seen along line 5-5 of FIG. 4 schematically illustrating the isolation system of FIG. 4; and
FIGS. 6-9 are section views in plan schematically illustrating isolation systems according to other embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
Referring now to the figures and, in particular, to FIG. 1, there is shown an aerospace vehicle 10 with an isolation system 20 according to one embodiment of the present invention. The illustrated aerospace vehicle 10 includes a kill vehicle 50 that is connected to a boost device 60, or boost vehicle. In other embodiments, the isolation system 20 can be used to isolate the transmission of shocks between portions of other aerospace vehicles and structures. Further, the isolation system 20 can be used for other vehicles and structures, such as for isolating navigational or guidance equipment from the structure of an aircraft, ship, or other vessel, for isolating an engine from the chassis of an automobile, for isolating a pump, motor, or other equipment from a building structure, and the like. Thus, the isolation system 20 can be used in a variety of applications.
The aerospace vehicle 10 shown in FIG. 1 can be launched from the ground by operation of the boost device 60. For example, the boost device 60 can include a solid or liquid fuel, which is combusted during a first stage of flight to propel the vehicle 10 into or above the atmosphere. The kill vehicle 50 is connected to the boost device 60 by releasable connections 70 so that the kill vehicle 50 can be released from the boost device 60 and proceeds in a second stage of flight to a target. For example, the releasable connections 70 can include an electrically-, pneumatically-, or hydraulically-actuated clamping system for connecting and releasing the boost device 60 and the kill vehicle 50. Alternatively, each releasable connection 70 can be a pyrotechnically-charged device that combusts to effect the release. The shock isolation system 20 shown in FIG. 1 is disposed between the boost device 60 and the kill vehicle 50 and, in particular, between the releasable connections 70 and boost device 60. Thus, the isolation system 20 can be released with the boost device 60 from the kill vehicle 50. In other embodiments of the present invention, however, the isolation system 20 can be disposed between the releasable connections 70 and the kill vehicle 50 so that the isolation system 20 is released from the boost device 60.
The first stage of flight of the aerospace vehicle 10 can end at a predetermined time, such as when substantially all of the fuel in the boost device 60 has been combusted, after a predetermined duration, or when the vehicle 10 reaches a predetermined altitude, location, or speed. A propulsion system 52 within the kill vehicle 50 can provide propulsion during the second stage of flight to propel or guide the kill vehicle 50 toward the target. The target can be, for example, a missile or other ballistic device, and the kill vehicle 50 can be designed to impact thereon to destroy or alter the course of the target. The boost device 60 can be discarded or retrieved after flight.
The foregoing description is an exemplary flight sequence, though it is understood that the sequence can differ in other embodiments of the present invention. For example, the aerospace vehicle 10 can be launched from an intermediate device such as an aircraft or a space-orbital structure, and/or the kill vehicle 50 can remain connected to the boost device 60 throughout the entire flight of the vehicle 10.
During the first stage of flight, a guidance system 62 in the boost vehicle 60 determines guidance information such as the location, orientation, and velocity of the vehicle 10. The guidance information can be used to control the combustion of the fuel in the boost device 60, the operation of a vane or other flight control device, and other aspects of the propulsion. Prior to the separation of the kill vehicle 50 from the boost device 60, at least some of the guidance information is communicated from the boost device 60 to the kill vehicle 50. In particular, the current location, orientation, and velocity of the vehicle 10 can be communicated from the guidance system 62 in the boost device 60 to a guidance system 54 in the kill vehicle 50. Communication of the guidance information can be achieved, for example, by an electronic transmission through a cable (not shown) connecting the guidance systems 62, 54.
The shock isolation system 20 includes a combination of linear bearing assemblies 30 and isolators 40. In the embodiment illustrated in FIGS. 2 and 3, each linear bearing assembly 30 includes a shaft member 32 and a linear bearing 34. The shaft members 32 are connected to c-shaped brackets 64 that are connected to the boost device 60 such that the shaft members 32 extend generally parallel in an axial direction of the vehicle 10. Each linear bearing 34 is connected to the kill vehicle 50 via an adapter 56 and configured to move axially on the respective shaft member 32. The linear bearings 34 can be constructed according to a variety of configurations, as is known in the art. For example, each linear bearing 34 can include a cylindrical raceway 36 or cage for holding a plurality of balls 38 in rolling contact with the shaft member 32 as the linear bearing 34 is moved axially on the shaft member 32. Thus, the bearing assemblies 30 allow a relative axial motion between the kill vehicle 50 and the boost device 60, i.e., the kill vehicle 50 and the boost device 60 can move axially toward or away from each other.
The isolators 40 are disposed so that relative motion between the boost device 60 and the kill vehicle 50 results in deformation of the isolators 40, thus damping the motion therebetween. For example, each isolator 40 can extend circumferentially around the shaft members 32 of the bearing assemblies 30, and two or more isolators 40 can be disposed on each shaft member 32 opposite the linear bearing 34 as shown in FIGS. 1-3 so that the isolators 40 damp motion of the bearings 34 on the shaft members 32 and, hence, relative motion between the boost device 60 and the kill vehicle 50.
The isolators 40 can be formed of elastomeric materials such as rubber or elastomerically deformable polymers. Alternatively, the isolators 40 can be springs, such as coil or Belleville springs configured to reduce the axial motion between the boost device 60 and kill vehicle 50. Further, in some embodiments, springs and elastomeric isolators can be used in conjunction, for example, with one of the elastomeric isolators configured opposite a linear bearing 34 from a Belleville spring.
The isolators 40 can be disposed between the boost device 60 and the kill vehicle 50 at positions other than on the shaft members 32 of the linear bearing assemblies 30. Thus, the isolators 40 can extend between the boost device 60 and the kill vehicle 50 and can be positioned separately from the linear bearing assemblies 30. For example, in the embodiment illustrated in FIGS. 4 and 5, two linear bearing assemblies 30 and four isolators 40 are disposed between the boost device 60 and the kill vehicle 50 in a generally planar and circular configuration with the linear bearing assemblies 30 at diametrically opposite circumferential positions.
Other alternative configurations for the isolators 40 and linear bearing assemblies 30 according to other embodiments of the present invention are schematically illustrated in FIGS. 6-9. For example, FIG. 6 illustrates a configuration of three circumferentially spaced linear bearing assemblies 30, the shaft member 32 of each linear bearing assembly 30 having two isolators 40 disposed thereon opposite the linear bearings 34. FIG. 7 illustrates a configuration of two linear bearing assemblies 30 and fourteen isolators 40. FIG. 8 illustrates a configuration of four linear bearing assemblies 30 and twelve isolators 40. FIG. 9 illustrates a configuration of three linear bearing assemblies 30 and twelve isolators 40. Similar to the isolators 40 shown in FIGS. 4 and 5, the isolators 40 of FIGS. 7-9 are provided separately from the linear bearing assemblies 30. It is understood that the embodiments illustrated in FIG. 6-9 are only examples of the many different configurations that are possible. In other embodiments, the isolators 40 and linear bearing assemblies 30 can be configured in non-circular configurations, e.g., generally in the shape of another polygon such as a square, rectangle, triangle, and the like. In addition, the isolators 40 and/or the linear bearing assemblies 30 can be disposed in asymmetric configurations, e.g., so that an elastic center of the isolation system 20 is not collinear with the axial center of the kill vehicle 50 and the boost device 60. By “elastic center” it is meant the location at which an axial force urging the boost device 60 and the kill vehicle 50 together results in equal deformation of each of the isolators 40. For example, if a center of gravity of the kill vehicle 50 and/or the boost device 60 are not located along an axis passing through the geometric centers thereof, the elastic center of the isolation system 20 can be made to correspond to the center of gravity of the kill vehicle 50 and/or the boost device 60.
In operation, the linear bearing assemblies 30 restrict the relative motion between the kill vehicle 50 and the boost device 60 to motion substantially in the axial direction of the shaft members 32. Transverse motion, i.e., perpendicular to the axial direction, and rotational motion about the axial direction between the boost device 60 and the kill vehicle 50 are thereby prevented. Thus, the guidance information communicated from the boost device 60 to the kill vehicle 50 will accurately describe the orientation of the kill vehicle 50.
Further, the isolators 40 damp the transmission energy in the form of shocks between the boost device 60 and kill vehicle 50, which can otherwise occur, e.g., due to the firing of the boost device 60. The shocks can be characterized by individual or repeated motions, e.g., vibrations that can be generally random or repetitive in nature. The isolators 40 can attenuate axial motion of the boost device 60 relative to the kill vehicle 50. Further, the isolators 40 can attenuate a relative rotational motion between the kill vehicle 50 and the boost device 60 about an axis transverse to the axial direction. For example, such a lateral motion results when one or more of the linear bearings 34 move independently, e.g., one or more of the linear bearings 34 move toward the kill vehicle 50 while one or more of the other linear bearings 34 move toward the boost device 60. As shown in FIG. 4, centers of gravity 58, 66 of the kill vehicle 50 and boost device 60, respectively, can each be located out of a plane defined by the isolators 40 and the linear bearing assemblies 30 to facilitate the attenuation of such a rotation of the centers of gravity 58, 66 about an axis transverse to the axial direction of the vehicle 10.
Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A shock isolation system for reducing a transmission of energy in the form of shocks between first and second devices, the system comprising:

at least two linear bearing assemblies extending substantially parallel in an axial direction between the first and second devices, each bearing assembly having a shaft member connected to one of the first and second devices and a linear bearing connected to tie other of the first and second devices, the linear bearings being configured to move axially on the shaft members such that the first and second devices are configured for relative motion therebetween in the axial direction and the bearing assemblies restrain a rotation between the first and second devices about an axis defining the axial direction; and

at least two isolators configured to be axially loaded by a relative motion between the first and second devices in the axial direction, the isolators thereby being deformed to at least partially reduce the transmission of energy between the devices.

2. A shock isolation system according to claim 1 wherein centers of gravity of the first and second devices are positioned out of a plane defined by at least some of the linear bearing assemblies and isolators.

3. A shock isolation system according to claim 1 wherein the linear bearing assemblies are configured to be independently axially moved such that the first device is configured to rotate relative to the second device about an axis transverse to The axial direction.

4. A shock isolation system according to claim 1 wherein the linear bearing of each respective bearing assembly extends circumferentially around the shaft member of the respective bearing assembly and has a plurality of balls for rollably contacting the shaft member.

5. A shock isolation system according to claim 1 wherein at least two of the isolators extend circumferentially around the shaft member of a respective one of the linear bearing assemblies, the isolators being positioned opposite the linear bearing of the respective bearing assembly such that at least one of the isolators is compressed when the linear bearing of the respective bearing assembly moves axially.

6. A shock isolation system according to claim 1 wherein each isolator extends between the first and second devices such that the isolators are compressed when the first and second devices are moved relatively toward each other.

7. A shock isolation system according to claim 1 wherein the isolators are formed of at least one of the groups consisting of rubber and elastically deformable polymers.

8. A shock isolation system according to claim 1 wherein at least some of the isolators comprise springs.

9. A shock isolation system according to claim 1 wherein the linear bearing assemblies and isolators are arranged in a substantially planar and polygonal configuration.

10. A shock isolation system according to claim 1 wherein at least one of the first and second devices is a boost vehicle configured to provide thrust for propulsion.

11. A shock isolation system according to claim 10 wherein at least one of the first and second devices is a kill vehicle.

12. An aerospace vehicle for impacting a target, the aerospace vehicle having a shock isolation system for reducing a transmission of energy in the form of shocks therein, the vehicle comprising:

a boost device structured to provide thrust for moving the aerospace vehicle;

a kill vehicle configured for impacting upon the target;

at least two linear bearing assemblies extending substantially parallel in an axial direction between the boost device and the kill vehicle, each bearing assembly having a shaft member connected to one of the boost device and the kill vehicle and a linear bearing connected to the other of the boost device and the kill vehicle, the linear bearings being configured to move axially on the shaft members such that the boost device and the kill vehicle are configured for relative motion therebetween in the axial direction and the bearing assemblies restrain a rotation between the boost device and the kill vehicle about an axis defining the axial direction; and

at least two isolators configured to be axially loaded by a relative motion between the boost device and the kill vehicle in the axial direction, the isolators thereby being deformed to at least partially reduce the transmission of energy between the boost device and the kill vehicle.

13. An aerospace vehicle according to claim 12 wherein the kill vehicle is releasably connected to the boost device.

14. An aerospace vehicle according to claim 12 wherein centers of gravity of the boost device and the kill vehicle are positioned out of a plane defined by at least some of the linear bearing assemblies and isolators.

15. An aerospace vehicle according to claim 12 wherein the linear bearing assemblies are configured to be independently axially moved such that the kill vehicle is configured to rotate relative to the boost device about an axis transverse to the axial direction.

16. An aerospace vehicle according to claim 12 wherein the linear bearing of each respective bearing assembly extends circumferentially around the shaft member of the respective bearing assembly and has a plurality of balls for rollably contacting the shaft member.

17. An aerospace vehicle according to claim 12 wherein at least two of the isolators extend circumferentially around the shaft member of a respective one of the linear bearing assemblies, the isolators being positioned opposite the linear bearing of the respective bearing assembly such that at least one of the isolators is compressed when the linear bearing of the respective bearing assembly moves axially.

18. An aerospace vehicle according to claim 12 wherein each isolator extends between the boost device and the till vehicle such that the isolators are compressed when the boost device and the kill vehicle are moved relatively toward each other.

19. An aerospace vehicle according to claim 12 wherein the isolators are formed of at least one of the group consisting of rubber and elastically deformable polymers.

20. An aerospace vehicle according to claim 12 wherein at least some of the isolators comprise springs.

21. An aerospace vehicle according to claim 12 wherein the linear bearing assemblies and isolators are arranged in a substantially planar and polygonal configuration.