JPS59188561A - Angular speed detector - Google Patents

Abstract

PURPOSE:To simplify constitution and improve mechanical strength and reliability by using at least one accutron tuning fork and 2n (n: natural number) sheets of rectangular piezoelectric bimorph as principal elements. CONSTITUTION:The driving part 10 consisting of the accutron tuning fork and a detection part 20 consisting of a piezoelectric element are fixed to vehicle respectively, and when the vehicles has a rotating angular speed, respective detecting elements generate composite electric signals. The detecting elements 20c and 20d are rectangular piezoelectric bimorph elements in the same shape, and the main surfaces of said bimorph elements are connected electrically to the mutually opposite main surfaces of said tuning fork in the lengthwise direction on the main surface. Consequently, the constitution is simplified, and the mechanical strength and reliability are improved.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an angular velocity detection device for various vehicles, and particularly to an angular velocity detection device for determining the relative turning angle of a vehicle from a reference position. be.

Conventional configurations and their problems In recent years, vehicle orientation sensors have been actively developed due to the desire to add new functions to various vehicles, including automobiles. Generally speaking, one-type orientation sensors can be broadly classified into the following two types. That is.

A: A method that determines absolute vapor direction from quantities that specify coordinates attached to the earth.

B: A method in which the relative direction from a reference position appropriately determined by the user of the sensor is determined from the amount of the person other than the person mentioned above.

As long as the vehicle is traveling on a surface with clear coordinates, a vehicle is not required as a direction sensor. Typical examples of B include [1] Fluid type (gas rate gyro), (
2) There is a vibration type (angular velocity detection device using piezoelectric effect), etc.

Some of the above-mentioned fluid type systems are configured to convert the deviation of the gas flow caused by Coriolika caused by the rotation of the vehicle into a temperature change, and convert the amount of change into an electric signal. The rotational speed of the vehicle is determined from the electrical signal level, and the rotational speed is time-integrated using known electrical circuit technology to determine the relative rotational angle He from the reference position of the vehicle before its rotational movement.

The above vibration type will be explained with reference to one drawing.

FIG. 1 is a perspective view of a conventional angular velocity detection device using a piezoelectric effect. 10! L and 10b are drive elements made of piezoelectric bimorphs, and 20&+20b are sensing elements made of piezoelectric bimorphs.

4Fi This is a base substrate on which the above drive element is fixed.

3a and 3b are joints that connect the piezoelectric bimorphs. Reference numeral 6 indicates a direction in which the drive element vibrates in an arc in the thickness direction of the drive element, and reference numeral 6 indicates a rotation axis of the rotation system. To explain the operation of the angular velocity detection device configured as above, the sensing element made of a piezoelectric bimorph and the driving element are connected through a joint at an angle of approximately 90 degrees, and the driving element is arranged in an arc shape on its main surface. When there is an angular velocity on the rotational axis of the vibrating and rotating system, the main surface is bent by Coriolis, and an electric signal proportional to the angular velocity is generated due to the piezoelectric effect. This electrical signal is time-integrated using known electrical circuit technology to determine the relative rotational angle from the reference position of the vehicle before its rotational movement. However, the above two types of conventional examples have the following problems.

(1) In the case of a "fluid type" angular velocity detection device 1) There is a driving device for forming a gas flow. That is, it is necessary to change the amount of mechanical change in the rotation of the vehicle, which requires extra equipment.

2) Deviation of the gas flow in response to the rotation of the metal In order to convert the amount of change, which is not converted into an electrical signal, into an electrical quantity, a change in the gas flow that responds to the deviation of the gas flow is used. One set of thermistor is required.

(II) In case of "r vibration type" angular velocity detection device 1) In commercially available devices, the detection element is vibrated back and forth in an arc shape in a case with a small inner diameter, so there is a There is a risk that the sensing elements may come into contact with each other, so a very high level of assembly precision is required.

2) Since the driving element is composed of two piezoelectric bimorphs, there is a difference in the resonant frequency of each bimorph, and when driving the two piezoelectric bimorphs at the average frequency of the two resonant frequencies, each The vibration displacement of the bimorph decreases from that of the resonant frequency each year, and there is a possibility that the sensitivity of the detection output to a constant angular velocity decreases.

3) Since there are a large number of parts such as the piezoelectric bimorph as the main component and joints, the manufacturing process tends to be complicated due to the large number of electrical connections and adhesive connections.

OBJECTS OF THE INVENTION An object of the present invention is to provide an angular velocity detection device for a vehicle that solves all of the above-mentioned problems of the conventional B method.

Structure of the Invention The angular velocity detection device of the present invention has at least one Accutron tuning fork and 2n (n: natural number) rectangular piezoelectric bimorphs as main components, and has a main component of each of the tuning forks. One bimorph is attached to each of the main surfaces of the tuning fork on opposite sides in the longitudinal direction so as to share the longitudinal direction with the main surface of the tuning fork so as to be electrically conductive, and The element section installed on the rotary body substantially parallel to the rotational axis direction of the rotary body and the steel plates serving as each member of the tuning fork are bent by receiving Coriolis of opposite phase to each other as the rotary body rotates. , a 7ti-coupled band-pass filter that passes the combined electrical signals outputted from each set of bimorphs, an AC amplifier that amplifies the signal that has passed through the filter, and a current signal that has passed through the amplifier. a phase detection circuit that performs full phase detection; an Accutron drive circuit that generates an alternating current voltage to be applied to the Accutron tuning fork and the detection circuit; It is equipped with a low-pass filter that extracts an electrical signal generated when the bimorph bends in the thickness direction in response to the rotational angular velocity, and a DC amplifier that amplifies the signal after passing through the filter, and detects the entire angular velocity of the rotation system. This allows the configuration to be simplified.

DESCRIPTION OF EMBODIMENTS An angular velocity detection device according to the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing one specific example of the detection device according to the present invention, and each component indicated by arrows, numbers, and letters and its operation will be explained in sequence.

A driving section 1o consisting of an Accutron tuning fork and a detecting section 2o consisting of a piezoelectric element are each fixed to the vehicle, and when a displacement rate of the direction angle, that is, a rotational angular velocity occurs in the vehicle, the detecting section 1o detects a signal from each detecting element corresponding to the angular velocity. A composite electrical signal is generated.

Reference numeral 30 denotes a band pass filter for passing the composite electric signal, and serves to remove various noises other than the signal contained in the signal from the detection section 2o.

4o is an AC amplifier for amplifying the signal after the band-pass filter, and 50 is a phase detection circuit for detecting the phase of the current signal. Reference numeral 60 denotes an Accutron drive circuit that generates an AC voltage to be applied to the drive unit 1o and the detection circuit 6°, which plays the role of providing a drive voltage to the drive unit 1o, and also plays the role of supplying the drive voltage to the phase detection circuit 50vC. Each of these serves as a reference signal for activating the detection function. 7° is the phase detection circuit 6
A low-pass filter is shown for extracting a signal corresponding to the rotational angular velocity of the detection unit 2o from the detection signal detected by the detector 2o. 8oFi 9Baco which amplifies the signal after passing through the low pass filter! A DC amplifier is shown, from which the output signal Ω corresponds to the relative rotational angular velocity of the vehicle. As inferred from the above explanation, the solid line with arrows represents the flow of electrical signals.

3 to 5 are cross-sectional views for explaining the specific structure and function of elements 10 and 20 in the embodiment shown in FIG. 2.

First, FIG. 3 is a sectional view showing the structure of the element section, and FIG. 4 is an enlarged view of the section taken along the line A-5 in FIG. 3. 1oC
The Accutron tuning fork is provided with an iron piece around which a magnet and a coil are wound at both ends 7a and 7b of its longitudinal branches, and is a driving element in which the main shaft of the tuning fork is fixed to the pace board 41L.

20CI 2od is a rectangular piezoelectric bimorph with the same shape, and the length direction on the main surface of the bimorph is arranged parallel to the length direction on the main surface of each of the tuning forks, and This is a sensing element mounted on the main surface (referring to 81L and 8b or 80 and 8d in FIG. 4) so as to electrically conduct the main surface of the bimorph. The element section is arranged such that the length direction of the Accutron tuning fork functioning as the drive element and the length direction of the bimorph functioning as the detection element are substantially parallel to the rotation axis 51L of the rotation system. It is installed in

FIG. 5 is a cross-sectional view showing the function of the element portion, and FIG. 6 is an enlarged view of the cross section taken along the line B--B in FIG. 70,7d
, 76.7f are electrical connection terminals for supplying power to the vibrator that drives the Accutron tuning fork. When the driving element 10d, which is an Accutron tuning fork, is driven by a sine wave electric signal from the terminal portion, each of the two tuning forks vibrates in opposite phases to each other in the width direction. The vibration 6a also occurs in the rectangular piezoelectric bimorph 206 + 2 Of that functions as a detection element due to the vibration. When the driving element and the sensing element rotate about the longitudinal direction, Coriolis of opposite phase is generated in each of the tuning forks. The Coriolis becomes stronger as it is longer in the length direction than the base part of the tuning fork, so it is bent into a dead line shape from the base part. The bent 11S-'; Therefore, from the bimorph that is brought into close contact with the main surface of each of the Accutron tuning forks.

The positive piezoelectric effect generates an electrical signal proportional to the angular velocity of said rotation. In order to remove error components caused by external vibrations of centrifugal force and acceleration components, the front and back electrodes of the two rectangular piezoelectric bimorphs, which serve as the sensing elements (described below with reference to FIG. 4), are made to have equal potential. The electrical connections 9a and 9b and 9C are connected at 9dil to significantly reduce the influence of the external vibration. As a result, only a composite electric signal 90 proportional to the angular velocity is taken out between one end of 9a and 9b and one end of 90 and 9d. Although the above explanation deals with the case where two rectangular piezoelectric bimorphs are used as the sensing elements, in principle, as described in the structure of the invention,
An even number of bimorphs may be used. The angular velocity detection device according to the present invention may be used in vehicles, ships, aircraft, robots, etc., and the device can be used for attitude control and automatic operation.

Effects of the Invention As is clear from the above description, the angular velocity detection device based on the present invention has a simple configuration and is easy to assemble (manufacture). In addition, the driving part is the well-known Accutron tuning fork, and the piezoelectric bimorph as the detection element is also tightly attached to the steel plate of the tuning fork, so it has high mechanical strength and high reliability, making it suitable for industrial use. The value is great.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional angular velocity detection device, FIG. 2 is a block diagram for explaining a configuration example of the angular velocity detection device of the present invention, and FIGS. 3 and 4 explain the entire configuration of one embodiment. FIGS. 5 and 6 are cross-sectional views for explaining the functions of one embodiment. 3a+ 3b...Joint, 4,4a...
・Base board, 5.5 &... Rotating shaft, 6, 6a
...Direction of bending vibration, 7a, 7b, old...electromagnet, 7C, 7d, 7e. 7f... Electrical connection terminal, 8J 8b, sc
, sa...Main surface of Accutron tuning fork, 9! L,
9b, 90°13be=2゛9d... Front and back electrodes of rectangular piezoelectric bimorph,
10゜1 C1, I Qb, 100,106----
, drive element, 201 20! L, 20b, 20Q, 20
(1...detection element, 30...bandpass filter, 40...AC amplifier, 5o...
Detection circuit, 60... Accutron drive circuit, 7
0...Low pass filter, 80...DC amplifier, 9o...Synthesized electrical signal. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 5 Figure 4

Claims (1)

[Claims] The main components include at least one Accutron tuning fork and 2n (n: natural number) rectangular piezoelectric bimorphs, and the bimorphs are arranged on the main surfaces of each tuning fork on opposite sides in the longitudinal direction. One of each of the tuning forks is mounted so as to share the length direction with the main surface of the tuning fork and be electrically conductive with the main surface of the tuning fork, and the length direction of both of the tuning forks is substantially parallel to the rotational axis direction of the rotating body. As the rotating body rotates, the element section installed on the rotating body and the steel plate serving as each member of the tuning fork are bent by receiving Coriolis of opposite phase to each other as the rotating body rotates, and each set of bimorphs is output accordingly. a band-pass filter that allows a synthesized electrical signal to pass through; an AC amplifier/amplifier that fully amplifies the signal that has passed through the filter; a phase detection circuit that fully detects the phase of the current signal that has passed through the amplifier; and the Accutron tuning fork. An Accutron drive circuit generates an alternating current voltage to be applied to the detection circuit, and the bimorph attached to the main surface of the Accutron tuning fork bends in the thickness direction in accordance with the rotational angular velocity based on the detection signal detected by the detection circuit. An angular velocity detection device configured to be able to detect the angular velocity of the rotation system, comprising a low-pass filter for extracting an electrical signal generated by the above-mentioned rotation, and a DC amplifier for amplifying the entire signal after passing through the filter.