Proof mass for maximized, bi-directional and symmetric damping in high g-range acceleration sensors

• US 8,191,420 B2
• Filed: 08/12/2010
• Issued: 06/05/2012
• Est. Priority Date: 08/13/2009
• Status: Active Grant

• Current Assignee: PCB Piezotronics of North Carolina, Inc. (Amphenol Corporation)
• Original Assignee: Meggitt San Juan Capistrano Inc. (Parker-Hannifin Corporation)
• Inventors: Wilner, Leslie Bruce, Kwa, Tom
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US12/806,415
• Publication Number:
  US 20110041608A1
• Time in Patent Office: 663 Days
• Field of Search: 735/141.4, 735/143.3, 735/143.4, 735/140.5, 735/140.6, 735/140.7, 735/141.2, 735/141.6, 735/143.6, 735/143.8, 735/142.9
• US Class Current: 73/514.16
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 3/0078 Constitution or structural means for improving mechanical properties not provided for in B81B3/007 - B81B3/0075
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/08 with conversion into electric or magnetic values
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 2015/0882 for providing damping of vibrations

Abstract

A new high G-range damped acceleration sensor is proposed with a proof mass optimized for maximized, bi-directional and symmetrical damping to accommodate acceleration ranges above and beyond several thousand G'"'"'s. In order to achieve the maximum, bi-directional and symmetrical damping, the high G-range acceleration sensor is designed to have minimum amount of mass in the proof mass while maximizing its surface areas. Such high G-range damped acceleration sensor can be applied to any application in which damping (or suppression of ringing) is desired at quite high frequencies.

Claims

1. An acceleration sensor, comprising:

a proof mass having opposing and alternating open and closed cells with flat surfaces adjacent to each other and separated by thin walls at cell boundaries in order to retain minimum amount of mass and to achieve maximum surface areas for maximized damping of the sensor;

one or more dampers on both side of the proof mass to damp motion of the proof mass;

one or more measuring supports connecting the proof mass to a frame;

said frame connecting the sensor to a subject being measured to measure the acceleration of the subject.

2. The sensor of claim 1, further comprising:

two cantilever measure beams, one along either long side of the proof mass to measure acceleration through a plane.

3. The sensor of claim 2, further comprising:

a pair of cantilever beams outside the cantilever beams, providing electrical pathways from the measure beams to the frame.

4. The sensor of claim 2, further comprising:

a pair of cantilevers along short ends of the proof mass, providing electrical pathways from the proof mass to the frame, and also gives mechanical support against accelerations transverse to the measure beams.

5. The sensor of claim 1, wherein:

each of the one or more measuring supports further comprises piezoresistive gages, grooves, and electrical contacts.

6. The sensor of claim 1, wherein:

the surface areas on two opposite sides of the proof mass are of approximately equal size in order to achieve symmetrical damping of the sensor.

7. The sensor of claim 1, wherein:

the proof mass has two opposite surfaces in order to achieve bi-directional damping of the sensor.

8. The sensor of claim 1, wherein:

each damper is a squeezed film of gas.

9. The sensor of claim 1, wherein:

the dampers act approximately equally on both sides of the proof mass in order to avoid false signals from rectification of vibration.

10. The sensor of claim 1, wherein:

the sensor has a light-weight structure in the form of surfaces held together by a sufficiently rigid frame to maximize the capture of the motion coming from both sides of the proof mass depending on the direction of acceleration applied to the sensor.

11. The sensor of claim 1, wherein:

the cells are arranged in a checkerboard manner.

12. The sensor of claim 1, wherein:

the cells are arranged in row patterns.

13. The system of claim 1, wherein:

boundaries of the cells are formed with visible and hidden narrow walls.

14. The sensor of claim 13, wherein:

The walls are very thin and narrow, while still providing good rigidity to the structure of the acceleration sensor.