Instrument for measuring accelerations, particularly gravitation components for goniometry

• US 5,022,264 A
• Filed: 11/08/1989
• Issued: 06/11/1991
• Est. Priority Date: 11/07/1988
• Status: Expired due to Fees

• Current Assignee: Wyler AG IM Holderli Ch-8405
• Original Assignee: Wyler AG
• Inventors: Stauber, Siegfried T.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/434,437
• Time in Patent Office: 580 Days
• Field of Search: 73/517 R, 73/497, 73/382, 73/382 G, 331/66, 361/280
• US Class Current: 73/382.00R
• CPC Class Codes: G01D 5/2417 by varying separation
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

For the measurement of accelerations, e.g. gravitation components for goniometry, in the oscillating circuit of two RC oscillators capacitors are provided, which in a common, metallic casing between two electrode plates (2,3) have a spring-elastically held, common, circular deflection part. In order to avoid dielectric interference, the electronic means are arranged on one side of the instrument, are surrounded by a metallic cover and their electrical connection to the more remote electrode plate takes place by a wire, which is passed in contact-free manner through a central hole in the circular deflection part and the closer electrode plate. The spacing between the deflection part and the electrode plates remains constant in the case of a non-deflected deflection part, in that its size forms a ratio _E - _M : _M to the thickness of the spacers insulating the electrode plates from the metallic casing, _E corresponding to the thermal expansion coefficient of the spacers and _M to that of the metallic casing.

Claims

1. An instrument for measuring acceleration, comprising:

a circular, metallic deflection part having a hole defined through its center;

two electrode plates having a hole defined through their centers;

a common casing having two parts, said deflection part held in a spring-elastic, membrane-like spaced manner between said two electrode plates and said deflection part and said two electrode plates in turn being placed between said two parts of said common casing, said deflection part and said electrode plates forming two adjacent capacitors;

an electrical connecting wire; and

electronic means for measuring acceleration in response to changes in capacitance of said capacitors;

wherein said capacitors are electrically connected to said electronic means, and said electrical connecting wire is passed in a contact-free manner through said central hole in said deflection part and through holes in both electrode plates, said wire connecting the electrode plate more remote from the electronic means to the electronic means.

2. An instrument according to claim 1, wherein at least one RC oscillator is provided for computational temperature compensation and which, as a reference oscillator, has a constant oscillating frequency.

3. An instrument according to claim 1, wherein to the part of a metallic instrument casing forming the electrical grounding carrying the electronic means is fixed with electrical contact a metallic cover surrounding said means, the other part of the metallic casing forming a casing block, on which are provided fastening means and/or a reference surface for angular measurments.

4. An instrument for measuring acceleration as claimed in claim 1, further including two additional electrode plates and an additional deflection part disposed therebetween and supported by said common casing, said additional deflection part being arranged perpendicular to the first-mentioned deflection part.

12. An instrument according to claim 1 for measuring acceleration, comprising:

two circular, metallic deflection parts having a hole defined through their centers;

a common casing having a plurality of parts, said two pairs of adjacent capacitors being positioned offset to each other at 90°

to the outside surface of one of said common casing parts; and

electronic means for measuring acceleration in response to changes in capacitance of said two pairs of capacitors.

13. An instrument for measuring acceleration as claimed in claim 12, further including two additional electrode plates and an additional deflection part disposed therebetween and separated by said common casing, said additional deflection part being arranged perpendicular to the said other deflection parts.

5. An instrument for measuring acceleration, comprising:

a circular, metallic deflection part having a hole defined through its center;

two electrode plates having a hole defined through their centers;

a common casing having two parts, each part having openings defined therethrough to the outside thereof, said deflection part being held in a spring-elastic, membrane-like spaced manner between said two electrode plates, and said deflection part and said two electrodes in turn being placed between two parts of a common casing, said deflection part and said electrode plates forming two adjacent capacitors;

at least one electrically conducting extensions located adjacent to and at right angles to said central holes of said electrode plates, said at least one extension passing through opening defined in said common casing;

an electrical connecting wire; and

electronic means for measuring acceleration in response to changes in capacitance of said capacitors;

wherein said capacitors are electrically connected to said electronic means, and said electrical connecting wire is passed in a contact-free manner through said central hole in said deflection part and through holes in both electrode plates, through said at least one electrically conducting extension, and through said opening of one part of said common casing, where said wire is soldered to the extension on the electrode plate more remote from the electronic means to connect to the electronic means.

6. An instrument for measuring acceleration, comprising:

a circular, metallic deflection part having a hole defined through its center;

two metallic electrode plates having a hole defined through their centers;

a metallic common casing having two parts;

insulating spacers, said deflection part held in a spring-elastic, membrane-line, spaced manner between said two electrode plates, said electrode plates being positioned between and spaced from said two casing parts by said insulating spacers, said deflection part and said electrode plates forming two adjacent capacitors; and

electronic means for measuring acceleration in response to changes in capacitance of said capacitors;

whereby in situations where the deflection part is not deflected and only temperature changes are considered, the spacing between the electrode plates and said deflection part remains constant, even after temperature changes, by virtue of said spacing forming the ratio _E - _M ;

_M to the thickness of spacers, _E corresponding to the thermal expansion coefficient of the insulating material of the spacers and _M corresponding to the thermal expansion coefficient of the metallic casing.

7. An instrument according to claim 6, wherein the insulating spacers have recesses or cavities.

8. An instrument according to claim 7, wherein the insulating spacers are shaped like a spoked wheel with at least three spokes.

9. An instrument for measuring acceleration, comprising:

a circular, metallic deflection part having a hole defined through its center;

two electrode plates having a hole defined through their centers;

a common casing having two parts, each part having openings defined therethrough to the outside thereof, said deflection part being held in a spring-elastic, membrane-like spaced manner between said two electrode plates, and said deflection part and said two electrodes in turn being placed between two parts of a common casing, said deflection part and said electrode plates forming two adjacent capacitors;

at least one electrically conducting tubularly shaped extensions located adjacent to and at right angles to said central holes of said electrode plates, said at least one extension passing through opening defined in said common casing;

an electrical connecting wire;

an insulating spacer, said insulating spacer shaped like a spoked wheel with a central hub, said tubularly shaped extension passing through said central hole, and thereby centering said electrode plate having said tubularly shaped extension with respect to said spacer; and

electronic means for measuring acceleration in response to changes in capacitance of said capacitors;

wherein said capacitors are electrically connected to said electronic means, and said electrical connecting wire is passed in a contact-free manner through said central hole in said deflection part and through holes in both electrode plates, through said at least one electrically conducting extension, and through said opening of one part of said common casing, where said wire is soldered to the extension on the electrode plate more remote from the electronic means to connect to the electronic means.

10. An instrument for measuring acceleration, comprising:

a circular, metallic deflection part having a hole defined through its center, said deflection part being spirally surrounded by at least three bands in an angular range of more than 360°

, said bands being connected to a circular outer rim, the deflection part, the bands and the outer ring being shaped from common metal foil and lying in a single plane;

two electrode plates having a hole defined through their centers;

a common casing having two parts, said deflection part held in a spring-elastic, membrane-like spaced manner between said two electrode plates and said outer rim connected to said deflection part being fixed between the two casing parts, said deflection part and said two electrode plates being placed between said two parts of said common casing, said deflection part and said electrode plate forming two adjacent capacitors; and

electronic means for measuring acceleration in response to changes in capacitance of said capacitors;

wherein said capacitors are electrically connected to said electronic means, and said electrical connecting wire is passed in a contact-free manner through said central hole in said deflection part and through holes in both electrode plates, said wire connecting the electrode plate more remote from the electronic means to the electronic means.

11. An instrument according to claim 10, wherein the circular outer rim surrounding the deflection part is held between circular, planar rims of the two casing parts so as to engage on the same and projections projecting radially from the outer rim project into a circumferential groove formed between the casing parts, the latter being formed from the same metallic material or a material with the same thermal expansion coefficient as the deflection part and the extensions are soldered to the casing parts within said circumferential groove.