Inclination sensor

• US 5,261,279 A
• Filed: 02/24/1992
• Issued: 11/16/1993
• Est. Priority Date: 03/05/1991
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wolf, Joerg, Zabler, Erich
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): BROCK, MICHAEL J
• Application Number:
  US07/840,328
• Time in Patent Office: 631 Days
• Field of Search: 73/505, 73/517 R, 33/308, 33/309, 33/346, 33/391, 33/366, 361/280
• US Class Current: 361/280
• CPC Class Codes: G01C 9/06 Electric or photoelectric indication or reading means
• CPC Class Codes: G01C 9/12 by using a single pendulum plumb lines G01C15/10

Abstract

A rotor for detecting inclination angles in relation to a defined rotational axis perpendicular to the direction of the field of gravity is proposed. In the center area of the sensor interior, enclosed by a housing, a mounting (25) is located, which is fixed in relation to the housing (30), and on which a seismic mass is suspended so that it can swing. The seismic mass is formed in the shape of a rotor (10) which is asymmetrical in respect to the mounting (25) and which can perform excursions around an axis defined by the mounting (25). Portions (11, 12) of the rotor (10) constitute electrodes of a capacitor arrangement. A border (20), fixed in relation to the housing (30), is disposed around the rotor (10) parallel to the axis defined by the mounting (25). The portions (21, 22, 23) of the border (20) constitute the backplate electrodes of the capacitor arrangement.

Claims

1. A sensor, for detecting inclination angles in relation to to a defined rotational axis (25) perpendicular to the direction of the field of gravity, with an interior enclosed by a housing (30), in a center volume of which a mounting (25) is located, which is fixed in relation to the housing, and with a seismic mass, which is suspended form the fixed mounting so that the seismic mass can swing,

characterized in that

the seismic mass is in the form of a rotor (10) which is asymmetrical with respect to the mounting (25),

the rotor (10) can perform excursions around an axis defined by the mounting (25),

portions (11, 12) of the rotor (10) constitute electrodes of a capacitor arrangement,

a segmented border (20), fixed in relation to the housing (30), is disposed around the rotor (10), and

segments (21, 22, 23) of the border (20) define counter-electrodes of the capacitor arrangement and cooperate with said electrode portions (11, 12) of the rotor to detect any rotation of said rotor (10).

2. A sensor in accordance with claim 1, characterized in that

the mounting (25) is formed in the shape of a pin which is connected with the housing (25) on at least one end,

the rotor (10) has a perforation (13), the cross section of which is larger than the cross section of the pin (25), and

the rotor (10) is placed on the pin (25) via the perforation (13).

3. A sensor in accordance with claim 2, characterized in that the pin has a rounded cross section.

4. A sensor in accordance with claim 2, characterized in that

the pin (25) has a cross section with at least one acute angle, and

the cross section of the perforation (13) has at least one angle, so that the perforation (13), together with the pin (25), forms a knife-edge seating for the rotor (10).

5. A sensor in accordance with claim 2, characterized in that

the rotor (10) is formed out of a circular disk for which segments have been cut in such a way that the perforation (13) is disposed near the center of the circle defined by said circular disk and

at least one rotor vane is defined on said rotor, so that when said rotor is in a rest position, the center of gravity of the rotor (10) is located below the mounting (25).

6. A sensor in accordance with claim 1, characterized in that

the border is arcuate but discontinuous so that arcuate partial borders (21, 22, 23) are formed.

7. A sensor in accordance with claim 1, characterized in that

the mounting (25) and the border (20) are placed on a substrate (31) which is fixedly connected with the housing (30).

8. A sensor in accordance with claim 7, characterized in that

the substrate (31) is a silicon wafer to which a sequence of thin layers, in particular silicon oxide layers and polysilicon layers, has been applied, and

the rotor (10), the mounting (25) and the border (20) are structured out of the sequence of thin layers in accordance with the methods of surface micromechanics and consist at least partially of polysilicon.

9. A sensor in accordance with claim 7, characterized in that

the rotor (10), the mounting (25) and the border (20) are structured in accordance with Lithographic/Galvanoforming (LIGA) techniques from a material selected from the group consisting of metal and plastic.

10. A sensor in accordance with claim 9, characterized in that

the rotor (10), the mounting (25) and the border (20) are applied to a silicon substrate.

11. A sensor in accordance with claim 1, characterized in that

the interior of the sensor is completely filled with a damping medium.

12. A sensor in accordance with claim 11, characterized in that

the specific weight of the rotor (10) differs from the specific weight of the damping medium in such a way that friction in the course of movement of the rotor (10) in relation to the damping medium results in aperiodic damping of the rotor (10).