Sensor for determining angular velocity with piezoceramic component formed as thickness shear oscillator

• US 5,247,252 A
• Filed: 01/29/1991
• Issued: 09/21/1993
• Est. Priority Date: 12/22/1988
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Kaiser, Hans-Jurgen, Boruschewitz, Manfred, Hamisch, Hansjoachim
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US07/646,605
• Time in Patent Office: 966 Days
• Field of Search: 324/160, 73/505
• US Class Current: 324/160
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces

Abstract

A sensor (10) for determining angular velocity includes one or a plurality of piezoceramic plates (11, 12, 31 to 34), which are suitably oriented with respect to the axis of rotation and execute shear oscillations with the aid of an exciting circuit. If the sensor (10) is located in a rotating system, piezoelectric charges are generated on specific plate surfaces by generated Coriolis forces (K_c). These charges represent a measure of the rotational velocity (Ω).

Claims

1. A sensor for determining an angular velocity comprising at least one piezoceramic element having a polar axis and formed as a thickness shear oscillator having flat surfaces and side surfaces arranged so that said polar axis is parallel to said flat surfaces and perpendicular to said side surfaces, said sensor having exciting electrodes located on said flat surfaces and measuring electrodes located on said side surfaces for measuring angular velocity proportional to charge of said piezoceramic element, so that shear oscillation in direction of said polar axis is produced and during rotation about a rotary axis extending perpendicular to said polar axis and parallel to said flat surfaces Coriolis forces are produced which cause charges on surfaces which are perpendicular to said polar axis and which represent a measure of the angular velocity of rotation of said piezoceramic element.

2. A sensor as set forth in claim 1, wherein said piezoceramic component has a nodal line, said sensor further comprising two mountings attached to said sensor in a region of the nodal line.

3. A sensor as set forth in claim 2, wherein said piezoceramic component has longitudinal groove means in the region of the nodal line for receiving said mountings.

4. A sensor as set forth in claim 1, further comprising elastic electrically conductive spring means for supporting said sensor in a frame.

5. A sensor as set forth in claim 1, wherein said piezoceramic component comprises two elements having their polar axes extending parallel to each other, and excited in antiphase with oscillations, the measuring electrodes of the two elements being connected to one another such that their measuring signals are summarized while interference charges induced by vibration, compensate one another.

6. A sensor as set forth in claim 1, wherein said piezoceramic component comprises two elements each having a pair of plates arranged on a common substrate and equi-directional polar axes, shear motion of the two pairs being excited in antiphase and cophasally diagonally.

7. A sensor as set forth in claim 1, wherein a harmonic signal generated at said measuring electrodes and dependent on an amplitude of oscillation, is tapped before filtering in a signal path and is used to control the oscillation amplitude.