As the market demands smaller and smaller devices, new methods of assembling parts within packages to maximize the use of volume must be determined. Typically package sizes include the required parts plus the supports and fasteners required to meet the design requirements. As devices are being designed to withstand high g environments, such as a gun launch, supporting the internal hardware becomes more and more critical and requires more advanced supports. Some devices, such as navigation systems, must withstand high g requirements while taking up less space.
The present invention provides systems and methods for protecting a hardware device from shock loads in a package. An embodiment of a system of the present invention uses a cupped spring washer (or Belleville washer) to apply required clamping loads to internal hardware of a package to meet high g environments while minimizing a total size of the package. Embodiments also apply proper clamping loads over a large range of deflection of the internal hardware without placing tolerancing constraints on the overall external package size. The benefits of embodiments of the system can include: 1) no additional printed wiring board area (except for the mounting surface); 2) adequate clamping over a large range of deflection and tolerance (self-adjusts); 3) no significant loss of clamping load due to temperature, time, or other environments; 4) high frequency shock attenuation; 5) very low cost and high reliability compared to threaded fasteners; 6) extremely gun hard friendly while maintaining clamping load before, during, and after gun launch.
Embodiments of the system provides adequate clamping load over a large range of deflection and require only minimal amounts of volume. Embodiments require no additional volume since the system self-adjusts for minimum and maximum material conditions. Also, since embodiments of the invention are truly springs, the supported hardware is more isolated from high frequency shock typically associated with set-forward pulse in high-g launch environments than with threaded fasteners.
Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings:
An embodiment of a cupped spring (or Belleville) washer 20 is shown in
A base 54 including a flange 56 with holes 58, which can be threaded, for fasteners 50 is then attached to the cover 42 via fasteners 50, which can be screws, through the respective holes 48, 58. The cover 42, depending on the intended use of the device 40, can include an attached external assembly 43. When fastened to the cover 42, the base 54 contacts the hardware 52 and applies a force to the hardware 52. The hardware 52, in turn, applies a force to and compresses the washer 20 against the base 54, thereby loading the washer 20 with a predetermined load. In this way, the washer 20 can provide a required load to the hardware 52 over a range of deflections of the washer 20 and tolerances of the hardware 52. The washer 20 can also reduce the amount of vibration transmitted to the hardware 52 from the washer 20 as compared to the prior art. The cover 42 and base 54 can apply a wide range of loads to the washer 20, ranging from small to the maximum strength of the materials. Depending on the application and the design of the washer 20, any load and load range a system could require, from very small load ranges (grams) to very large load ranges (many tons), can be provided.
Embodiments of the present invention provide ˜1300 lbs of clamping load at a minimum material condition (˜0.020″ deflection) and ˜2600 lbs of clamping load at a maximum material condition (˜0.080″ deflection).
While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.