Capacitive acceleration sensor having a movable mass and a spring element

• US 8,181,522 B2
• Filed: 10/20/2008
• Issued: 05/22/2012
• Est. Priority Date: 10/19/2007
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Scheuerer, Roland, Weber, Heribert
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US12/254,113
• Publication Number:
  US 20090100932A1
• Time in Patent Office: 1,310 Days
• Field of Search: 735/143.2, 735/141.7, 735/141.8, 735/143.6, 735/143.8, 735/142.9
• US Class Current: 73/514.32
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

An acceleration sensor having a mass which is movably supported outside its center of gravity, first electrodes on the mass and second electrodes located at a distance therefrom forming a capacitive sensor in order to determine a change in position of the mass as a function of time. At least one spring element which generates a restoring force when the mass is deflected from its neutral position is provided on the side of the mass facing the capacitive sensor. The mass may be obtained by being exposed from a material layer, and the mass is surrounded, at least at its side faces, by this material.

Claims

1. An acceleration sensor, comprising:

a mass which is movably supported outside a center of gravity of the mass;

first electrodes on the mass and second electrodes located at a distance therefrom forming a capacitive sensor in order to determine a change in position of the mass as a function of time; and

at least one spring element which generates a restoring force when the mass is deflected from a neutral position, the at least one spring element being provided on a side of the mass facing the capacitive sensor;

wherein the mass is obtained by being exposed from a material layer, and the mass is surrounded, at least at side faces, by a material of the material layer, and wherein at least one cavity is provided in the mass, and wherein the cavity is sealed by a diaphragm having a supporting base, and wherein the at least one spring element is formed by the cavity and the diaphragm.

2. The acceleration sensor as recited in claim 1, wherein capacitive sensors are provided at two oppositely situated boundary surfaces of the mass.

3. The acceleration sensor as recited in claim 1, wherein at least one of the first electrodes on the mass and the second electrodes located at a distance therefrom, have lateral structuring.

4. The acceleration sensor as recited in claim 1, wherein the diaphragm is integrated as one piece into an outer boundary surface of the mass.

5. The acceleration sensor as recited in claim 4, wherein only one partial section of a boundary line of the diaphragm is integrally joined to the outer boundary surface of the mass.

6. The acceleration sensor as recited in claim 1, wherein the at least one spring element has a plurality of cavities which are separated by diaphragms, respectively.

7. The acceleration sensor as recited in claim 1, wherein the mass has precisely one spring element which engages with an axis of symmetry outside the center of gravity of the mass.

8. The acceleration sensor as recited in claim 1, wherein the mass is situated in a cavity which is closed on all sides.

9. The acceleration sensor as recited in claim 8, wherein a pressure in the cavity differs from atmospheric pressure, and is less than atmospheric pressure.

12. The acceleration sensor as recited in claim 1, wherein the at least one spring element engages with only one outer boundary surface of the mass for supporting the movably supported mass.

10. A method of using an acceleration sensor, the acceleration sensor including a mass which is movably supported outside a center of gravity of the mass, first electrodes on the mass and second electrodes located at a distance therefrom forming a capacitive sensor in order to determine a change in position of the mass as a function of time, and at least one spring element which generates a restoring force when the mass is deflected from a neutral position, the at least one spring element being provided on a side of the mass facing the capacitive sensor, wherein the mass is obtained by being exposed from a material layer, and the mass is surrounded, at least at its side faces, by a material of the material layer, the method comprising:

measuring, using the acceleration sensor, a lateral acceleration in three spatial directions,

wherein at least one cavity is provided in the mass, and wherein the cavity is sealed by a diaphragm having a supporting base, and wherein the at least one spring element is formed by the cavity and the diaphragm.

11. A motor vehicle having an acceleration sensor, the acceleration sensor comprising:

a mass which is movably supported outside a center of gravity of the mass;

first electrodes on the mass and second electrodes located at a distance therefrom forming a capacitive sensor in order to determine a change in position of the mass as a function of time; and

at least one spring element which generates a restoring force when the mass is deflected from a neutral position, the at least one spring element being provided on a side of the mass facing the capacitive sensor;

wherein the mass is obtained by being exposed from a material layer, and the mass is surrounded, at least at side faces, by a material of the material layer, and wherein at least one cavity is provided in the mass, and wherein the cavity is sealed by a diaphragm having a supporting base, and wherein the at least one spring element is formed by the cavity and the diaphragm.