Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Reexamination Certificate
2000-06-29
2003-11-25
Kwok, Helen (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
C073S504160
Reexamination Certificate
active
06651498
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a vibratory gyroscope and a vibrator capable of being preferably used in this vibratory gyroscope.
2. Related Arts
Japanese laid-open publication Tokkaihei No.7-83671 has disclosed a vibratory gyroscope using a tuning-fork vibrator made by joining a total of three vibration pieces composed of a middle driving vibration piece and two detecting vibration pieces before being at both sides of the middle driving vibration piece all joined to a base part in one body.
FIG. 1
shows the composition of an example of such a vibratory gyroscope. In the example shown in
FIG. 1
, a tuning-fork vibrator
71
forming a vibratory gyroscope is composed of three vibration pieces which are composed of a middle driving vibration piece
73
and two detecting vibration pieces
72
and
74
arranged at both sides of it nearly in parallel with it, and a base part
75
with which the driving vibration piece
73
and the detecting vibration pieces
72
and
74
are joined in one body.
In the above-mentioned tuning-fork vibrator
71
, the driving vibration piece
73
is vibrated in the X-Z plane by a driving means (not shown) provided on the driving vibration piece
73
. And the left and right detecting vibration pieces
72
and
74
are resonated in the same X-Z plane. When a turning angular rate &ohgr; acts around the axis of symmetry Z of the tuning-fork vibrator
71
, a Coriolis force (f) acts on each of the detecting vibration pieces
72
and
74
. Since the detecting vibration pieces
72
and
74
are vibrating in the X-Z plane, vibration in the Y-Z plane is induced in the detecting vibration pieces
72
and
74
. A turning angular rate is measured by detecting this vibration by means of an detecting means (not shown) provided on each of the detecting vibration pieces
72
and
74
.
In a former vibratory gyroscope of the above mentioned composition, in case of forming the vibratory gyroscope by supporting the tuning-fork vibrator
71
, the vibrator
71
is supported by fixing the entire end part
76
of the base part
75
of the tuning-fork vibrator
71
opposite to the other end part at which the driving vibration piece
73
and the detecting vibration pieces
72
and
74
exist, or by fixing an unillustrated supporting vibration piece at a position of this end part
76
corresponding to the axis of symmetry Z. Therefore, it cannot be said that a Coriolis force generated by a turning angular rate is efficiently utilized for action of a detecting vibration in the detecting vibration pieces
72
and
74
, and there is a problem that the sharpness of resonance (Q value) of the detecting vibration in the Y-Z plane in the detecting vibration pieces
72
and
74
is low and the measurement sensitivity for a turning angular rate is low.
SUMMARY OF THE INVENTION
Recently, a vibratory gyroscope is used as a turning rate sensor in a vehicle control method of an automobile body turning rate feedback system. Such a system detects the direction of a steering wheel itself by a turning angle of the steering wheel. At the same time as this, the system detects a turning rate of the actually turning car body by means of a vibratory gyroscope. The system finds a difference between the direction of the steering wheel and the actual body turning rate by comparing them with each other, and attains a stable body control by compensating a wheel torque and a steering angle on the basis of this difference.
It is necessary to contain such a vibrator into a particular container package, which is then fixed on a fixing member such as a fixing plate. The fixing member is then fixed on a car body. In such a case, the vibrator is adhered onto the fixing plate to fix it thereon.
However, in a car body control system, a vibratory gyroscope and its vibrator is subjected to a wide range of environmental temperature, including high and low temperatures. Such temperature range is normally −40° C. to +80° C., and may be broader when more strict specification is applied. Particularly when applying a vibrator made of a piezoelectric single crystal, the temperature characteristics of the crystal also affects the performance of the gyroscope.
The inventors have tried to eliminate or reduce the temperature characteristics of the vibrator itself. However, when adhering such a vibrator onto a fixing plate and measuring a sharpness of resonance (Q value) of its driving vibration between −40° C. it +80° C., it was found that the Q value is substantially changed or deviated between −40° C. to +80° C. For example, if the Q value is substantially constant near room temperature, the Q value is largely changed when the environment temperature of the vibrator is changed towards −40° C. or +80° C.
An object of the present invention is to provide a vibratory gyroscope which can improve the sharpness of resonance (Q value) of a detecting vibration in a detecting vibration piece and can measure a turning angular rate with a sensitivity.
Another object of the invention is to provide an analyzing method for manufacturing a vibrator having a high sharpness of resonance of a detecting vibration in a detecting vibration piece, and a supporting method and a manufacturing method using this analyzing method.
Another object of the invention is, when adhering a vibrator onto a supporting member, to reduce the deviation of Q value of the driving vibration excited in the vibrator when the environmental temperature of a gyroscope is changed so that the temperature-dependent change of the performance of the gyroscope may be reduced.
A vibratory gyroscope of the present invention is a vibratory gyroscope for detecting a turning angular rate of rotation applied to a vibrator, which vibratory gyroscope a vibrator provided with a plurality of vibration pieces and a base part having the plurality of vibration pieces connected with it and is composed so as to obtain the turning angular rate on the basis of a detecting vibration excited in the vibrator according to the turning angular rate when giving a driving vibration to at least one of the vibration pieces, and supports the vibrator in a domain where the detecting vibration is smallest in the vibrator, said domain being in the vicinity of the center of gravity of the vibrator.
Preferably the vibrator is provided with a supporting hole in a domain where the detecting vibration is smallest in a state where the supporting hole is not provided in the vibrator and the vibrator is supported with or in the vicinity, preferably on or near the inner wall face of this supporting hole.
Supporting the vibrator in the vicinity of the supporting hole means supporting the surface of the vibrator within a range of 1 mm from the periphery of the supporting hole.
Another embodiment the present invention is a vibratory gyroscope for detecting a turning angular rate of rotation applied to a vibrator and the vibrator is provided with a plurality of vibration pieces and a base part having the plurality of vibrating pieces connected with it and the base part is provided with a supporting hole the gyroscope is composed so as to obtain the turning angular rate on the basis of a detecting vibration excited in the vibrator according to the turning angular rate when giving a driving vibration to at least one of the vibration pieces and the gyroscope is provided with a supporting means for supporting the vibrator with or in the vicinity of the supporting hole.
And the present invention is a vibrator formed out of a piezo-electric single crystal and comprises a plurality of vibration pieces each of which performs a bending-vibration and a base part having the plurality of vibration pieces connected with it and said base part is provided with a supporting hole for supporting said vibrator .
Another embodiment of the present invention is a vibratory gyroscope for detecting a turning angular rate of rotation applied to a vibrator, wherein the vibrator is provided with a plurality of vibration pieces and a base part having the p
Fujiwara Yuji
Gouji Shosaku
Kikuchi Takayuki
Osugi Yukihisa
Soma Takao
Burr & Brown
Kwok Helen
NGK Insulators Ltd.
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