Force or extension sensor

• US 5,827,980 A
• Filed: 02/11/1997
• Issued: 10/27/1998
• Est. Priority Date: 08/16/1994
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Gilch, Markus, Doemens, Gunter
• Primary Examiner(s): Dougherty, Elizabeth L.
• Application Number:
  US08/776,956
• Time in Patent Office: 623 Days
• Field of Search: 73/862.626, 73/862.68, 73/780, 73/DIG. 4
• US Class Current: 73/862.626
• CPC Class Codes: G01B 7/16 for measuring the deformation in a solid, e.g. by resistance strain gauge
• CPC Class Codes: G01L 1/142 using capacitors

Abstract

The force or extension sensor has a measuring capacitor (Mk) whose comb-like, interlocking electrode structures (Es1, Es2) can be adjusted in parallel with one another by two attachment points (Bp1, Bp2) as a function of the force (F) or the extension (E) to be measured. The total capacitance of the measuring capacitor (Mk) is determined by a parallel circuit having individual electrode pairs. A change in the total capacitance of the measuring capacitor (Mk) which is brought about by a change in the distances (d1) between the electrodes provides information on the force (F) or the extension (ε) to be measured. A change in the distances between the electrodes as a result of temperature-related extension is at least largely avoided by virtue of the fact that the attachment points (Bp1, Bp2) lie on a junction line (V1) which runs parallel to the direction of the electrodes (E1, E2) and is oriented at an angle (α) of 40° to 50°, preferably 45°, with respect to the direction of the force (F) or the extension (ε) to be measured.

Claims

1. A force or extension sensor with capacitive transducer, comprising:

a measuring capacitor having comb-like, interlocking electrode structures, which are electrically insulated from one another, the structures being adjustable in parallel with one another by two attachment points thereof as a function of a force or extension to be measured;

a total capacitance of the measuring capacitor being determinable by a parallel circuit having individual electrode pairs each of which being formed by a first electrode of a first electrode structure of the electrode structures, and an associated, adjacent second electrode of a second electrode structure of the electrode structures;

an electrode spacing, which can vary in accordance with the force or the extension to be measured, of the electrode pairs is, within an entire measuring range, small in comparison with a distance between the adjacent first and second electrodes, which are not associated with one another, of the first and second electrode structures;

the attachment points of the first and second electrode structures lie on a junction line which runs parallel to a direction of the first and second electrodes and which is oriented at an angle in the range of 40°

to 50°

with respect to the direction of the force or the extension to be measured.

2. The force or extension sensor as claimed in claim 1, wherein the junction line is oriented at an angle of 45°

with respect to the direction of the force or the extension to be measured.

3. The force or extension sensor as claimed in claim 1, wherein at least one electrode of each of the electrode pairs of the measuring capacitor has a smaller thickness in an outer overlapping area.