Structure of angular rate sensor

An angular rate sensor is provided which measures the angular rate of a moving object such as an automotive vehicle. The angular rate sensor includes an installation base and an oscillator. The oscillator is excited to oscillate in a preselected direction perpendicular to an axis of rotation of the moving object and provides a signal indicative thereof. The installation base is used for installation of the sensor on the moving object and has an improved orientation structure for orienting the oscillator relative to the installation base during installation of the oscillator on the installation base so that the oscillator may oscillate in the preselected direction. The angular rate sensor is disposed within a casing through improved vibration isolators for absorbing unwanted vibrations impinging upon an operation of the sensor.

What is claimed is:

1. An angular rate sensor apparatus for determining an angular rate of a moving object comprising:

a mounting member for mounting the angular rate sensor on the moving object;

a sensor unit including a base and an oscillator, the oscillator being mounted on said base and excited to oscillate so as to output a signal indicating an angular rate when subjected to rotation about a given axis; and

a vibration isolator system isolating said sensor unit from vibration transmitted from said mounting member, said vibration isolator system connecting said mounting member and said sensor unit so that an elastic center associated with said vibration isolator system coincides with the center of gravity of said sensor unit, whereby vibration-induced elastic moments about the center of gravity of the sensor unit are essentially avoided.

2. An angular rate sensor apparatus as set forth in claim 1, wherein said oscillator has a node and an oscillating portion having a length which extends parallel to the given axis of rotation, and wherein said base has a reference surface on which the node of said oscillator is attached, the reference surface being arranged parallel to the length of the oscillating portion.

3. An angular rate sensor apparatus as set forth in claim 1, wherein said vibration isolator system includes an elastic member whose elastic force acts flush with the base of said sensor unit.

4. An angular rate sensor apparatus as set forth in claim 1, wherein said vibration isolator system includes a cylindrical elastic member having a length which extends parallel to said base.

5. An angular rate sensor apparatus as set forth in claim 2, wherein said vibration isolator system includes an elastic member having a length which extends parallel to the length of the oscillating portion of said oscillator.

6. An angular rate sensor apparatus as set forth in claim 1, wherein said vibration isolator system includes an elastic portion and a holder portion secured on said mounting member to hold said sensor unit in a given direction relative to said mounting member.

7. An angular rate sensor apparatus as set forth in claim 6, wherein the base of said sensor unit includes a protrusion supported by the holder portion of said vibration isolator system.

8. An angular rate sensor apparatus as set forth in claim 7, wherein the protrusion is connected to the holder portion using a screw.

9. An angular rate sensor apparatus as set forth in claim 7, wherein the holder portion of said vibration isolator system includes a hole into which the protrusion of the base of said sensor unit is fitted.

10. An angular rate sensor apparatus as set forth in claim 1, wherein said mounting member is a box within which said sensor unit and said vibration isolator system is disposed, the box having formed on an inner wall a bearing base having a groove into which said vibration isolator system is fitted elastically.

11. An angular rate sensor apparatus as set forth in claim 1, wherein the oscillator of said sensor unit is a tuning fork oscillator including a pair of arms extending parallel to the given axis of rotation.

12. An angular rate sensor apparatus as set forth in claim 1, wherein said mounting member is a casing within which said sensor unit and said vibration isolator system are disposed, and further comprising a damper member disposed between an inner wall of the casing and said sensor unit.

13. An angular rate sensor apparatus as set forth in claim 12, wherein said damper member is formed on the inner wall of the casing at a given interval away from said sensor unit.

14. An angular rate sensor apparatus as set forth in claim 12, wherein said damper member is formed on said vibration isolator system at a given interval away from the inner wall of the casing.

15. An angular rate sensor apparatus as set forth in claim 12, wherein said vibration isolator system includes an elastic portion and a holder portion secured on said mounting member to hold said sensor unit in a given direction relative to said mounting member, and wherein said damper member is formed on the holder portion.

16. An angular rate sensor apparatus as set forth in claim 15, wherein the base of said sensor unit includes a protrusion supported by the holder portion of said vibration isolator system.

17. An angular rate sensor apparatus as set forth in claim 12, wherein the oscillator of said sensor unit is a tuning fork oscillator including a pair of arms extending parallel to the given axis of rotation.

18. An angular rate sensor apparatus as set forth in claim 12, wherein said damper member damps an impact acting in a shearing direction of said vibration isolator system.

19. An angular rate sensor apparatus as set forth in claim 12, wherein said damper member absorbs impacts acting in first and second direction perpendicular to each other both of which are oriented perpendicular to a shearing direction of said vibration isolator system.

20. An angular rate sensor apparatus as set forth in claim 19, wherein said damper member includes an L-shaped elastic member disposed at an inner comer of the casing.

21. An angular rate sensor apparatus as set forth in claim 19, wherein said vibration isolator system absorbs an impact acting in a third direction perpendicular to the first and second directions.

22. An angular rate sensor apparatus as set forth in claim 21, wherein a direction of oscillation of said oscillator when excited coincides with the first direction.

23. An angular rate sensor as set forth in claim 21, wherein said vibration isolator system includes an elastic member having a length extending in the third direction.

24. An angular rate sensor as set forth in claim 12, further comprising a signal processing circuit providing an excitation signal to excite said oscillator and receiving the signal outputted from said oscillator to determine the angular rate, said signal processing circuit being connected to said vibration isolator system.

25. An angular rate sensor apparatus as set forth in claim 12, further comprising a rectangular mount frame including first and second opposed walls and third and fourth opposed walls, attached to an inner wall of the casing, and wherein said vibration isolator system is supported by the first and second opposed walls so as to absorb an impact acting in a first direction parallel to the third and fourth opposed walls, said damper member being mounted on at least one of the third and fourth opposed walls to absorb an impact acting in a second direction perpendicular to the first direction.