Method of manufacturing a low density underwater accelerometer

• US 10,448,181 B2
• Filed: 06/06/2016
• Issued: 10/15/2019
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Goodemote, John H., Cummiskey, Ryan
• Primary Examiner(s): Tugbang, A. Dexter
• Application Number:
  US15/174,436
• Publication Number:
  US 20160279749A1
• Time in Patent Office: 1,226 Days
• CPC Class Codes: B23P 19/04 for assembling or disassembling parts
• CPC Class Codes: G01P 15/09 by piezoelectric pick-up
• CPC Class Codes: G01P 15/0907 of the compression mode type
• CPC Class Codes: G01P 15/0915 of the shear mode type
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

A method of manufacturing a low density accelerometer comprises the steps of: providing a rigid hollow housing having an upper member and a lower member and forming a groove circumferentially along an inner surface of the rigid hollow housing about a location where the upper member is configured to meet the lower member; providing a sensor assembly including a sensing element affixed to a solid proof mass; disposing the sensor assembly in the lower member of the rigid hollow housing, such that an outer edge of the sensing element engages and is in physical contact with the groove defined in the inner surface of the rigid hollow housing; and placing the upper member of the rigid hollow housing over the lower member of the rigid hollow housing, to enclose the sensor assembly within the rigid hollow housing, wherein the sensor assembly is in physical contact with the rigid hollow housing at the groove.

Claims

1. A method of manufacturing a low density accelerometer comprising the steps of:

providing a rigid hollow housing having an upper member and a lower member and forming a groove circumferentially along an inner surface of the upper member and lower member of the rigid hollow housing about a location where the upper member is configured to meet the lower member;

providing a sensor assembly including a sensing element affixed to a solid proof mass;

disposing the sensor assembly in the lower member of the rigid hollow housing, such that an outer edge of the sensing element engages and is in physical contact with the groove defined in the inner surface of the lower member of the rigid hollow housing; and

placing the upper member of the rigid hollow housing over the lower member of the rigid hollow housing, to enclose the sensor assembly within the rigid hollow housing, the outer edge of the sensing element of the sensor assembly in physical contact with the groove defined in the inner surface of the upper member of the rigid hollow housing.

2. The method of claim 1, wherein providing the sensor assembly including the sensing element affixed to the solid proof mass further comprises:

forming the sensing element as a piezoelectric ring;

forming a shoulder portion of the solid proof mass such that the shoulder portion has a form factor that corresponds to an aperture defined in the piezoelectric ring; and

inserting the shoulder portion into the aperture defined in the piezoelectric ring.

3. The method of claim 1, wherein said solid proof mass is affixed to the sensing element using an adhesive.

4. The method of claim 1, wherein the sensor assembly is enclosed within the rigid hollow housing by bonding together a bottom end surface of the upper member of the rigid hollow housing with a top end surface of the lower member of the rigid hollow housing.

5. The method of claim 1, wherein the rigid hollow housing is formed of alumina.

6. The method of claim 1, wherein the sensing element is formed of piezoelectric material.

7. The method of claim 6, wherein the piezoelectric material is a piezoelectric ceramic ring.

8. A method of manufacturing a low density accelerometer comprising the steps of:

forming a rigid hollow housing, having an upper member and a lower member;

creating a groove circumferentially along an inner surface of the upper member and lower member of the rigid hollow housing about a location where the upper member meets the lower member;

forming a sensor assembly, wherein forming the sensor assembly comprises the steps of;

forming a sensor element as a ring, an outside perimeter of the sensor element configured to engage the groove along the inner surface of the upper member and the lower member of the rigid hollow housing; and

affixing a solid proof mass to the sensor element, the solid proof mass being affixed to the sensor element centered at an aperture defining a center of the sensor element ring;

disposing the sensor assembly in the lower member of the rigid hollow housing, such that an outer edge of the sensor element engages and is in physical contact with the groove defined in the inner surface of the lower member of the rigid hollow housing; and

placing the upper member of the rigid hollow housing over the lower member of the rigid hollow housing so that a bottom end of the upper member engages a top end of the lower member to enclose the sensor assembly within the rigid hollow housing and retain the outer edge of the sensor element in the groove along the inner surface of the upper member and the lower member of the rigid hollow housing.

9. The method of claim 8, further comprising:

forming a shoulder portion of the solid proof mass, the shoulder portion having a form factor that corresponds to the aperture defined in the sensor element; and

inserting the shoulder portion into the aperture defined in the sensor element.

10. The method of claim 9, wherein said solid proof mass is affixed to the sensor element using an adhesive.

11. The method of claim 10, wherein the solid proof mass is affixed to the sensor element using epoxy.

12. The method of claim 8, wherein affixing the solid proof mass to the sensor element further comprises the steps of:

defining a threaded bore in the solid proof mass;

placing the sensor element on said solid proof mass such that the threaded bore is positioned approximately central to the aperture defining the center of the sensor element ring;

placing a Belleville washer on the sensor element, wherein an outer edge of the Belleville washer is in contact with the sensor element in an area proximal to an edge of the aperture; and

inserting a threaded fastener through the Belleville washer and the aperture in the sensor element, the threaded fastener engaging the threaded bore in the solid proof mass.

13. The method of claim 8, wherein the rigid hollow housing is formed of alumina.

14. The method of claim 8, wherein the sensing element is formed of piezoelectric material.

15. The method of claim 14, wherein the piezoelectric material is a piezoelectric ceramic ring.