JPH08114458A - Angular velocity sensor - Google Patents

Abstract

PURPOSE: To obtain the angular velocity sensor, which can readily hold a tuning- fork type vibrator and can readily perform casing, by providing a vibrating means, a supporting means, a circuit board and a protecting means approximately in parallel. CONSTITUTION: An angular velocity sensor 100 is formed of constant elastic alloy or the like, and a tuning-fork type vibrator 10 as a vibrating means having a sound piece 11, a sound piece 12 and a neck part 13 is constituted approximately in parallel with a stage 40 comprising metal material. Since machining such as drilling is not required in the vibrator 10 and the stage 40 for supporting the vibrator 10, the workability and the assembling property of the sensor 100 are improved. Since the height of the sensor 100 can be made low with respect to the stage 40, the sensor 100 can be made compact. Furthermore, a case for protecting the vibrator 10 is made to have the shape of a cup having the shallow bottom. Therefore, the case can be readily machined by press working. Furthermore, the supporting means is constituted of a supporting tool 30 and the stage 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor for detecting an angular velocity of a vehicle in a yaw direction and used for a vehicle suspension control, a navigation system and the like.

[0002]

2. Description of the Related Art Conventionally, as a sensor for detecting an angular velocity, a tuning fork vibrator is used to vibrate the tuning fork, and the Coriolis force acting on a detection element fixed on a vibrating member of the tuning fork is detected to detect the angular velocity. There is something that detects
As its structure, there is a structure in which a tuning fork type vibrator is held on a terminal base via a support rod and is casing in a cap-shaped case (Japanese Patent Laid-Open No. 5-45168). According to Japanese Patent Application Laid-Open No. 5-45168, the structure of the angular velocity sensor is such that a supporting rod for supporting the tuning fork type vibrator and lead terminals are implanted in the terminal base, and the vibrator is fixed on the tuning fork type vibrator by a lead wire. And the lead terminals are connected to the piezoelectric element for detecting the Coriolis force.

[0003]

However, in the above structure, since the holding means of the tuning fork type vibrator is only one support rod, the assembly is not easy, and the case has a deep cap shape. Therefore, it is difficult to manufacture the case by press working, and there is a problem that the angular velocity sensor cannot be quickly assembled and manufactured.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an angular velocity sensor which can easily hold a tuning fork type vibrator and can easily make a casing.

[0005]

In order to solve the above problems, the structure of the present invention is an angular velocity sensor for detecting an angular velocity, which comprises a vibrating means vibrating in a certain direction at a constant cycle, and the vibrating means. A drive unit that vibrates in a certain direction at a constant cycle, a detection unit that detects the Coriolis force generated when an angular velocity acts on the vibration unit, a support unit that fixes the vibration unit, and a drive unit electrically. A circuit board for driving and determining an angular velocity from the Coriolis force detected by the detection means, and a protection means for protecting the components of the angular velocity sensor such as the vibration means and the circuit board are provided, and the vibration means, the support means, and the circuit board are provided. It is characterized in that the protection means are provided substantially in parallel.

Further, the structure of the second invention is characterized in that the vibrating means has a positioning means for fixing to the supporting means.

According to the third aspect of the invention, an electrically high resistance portion is provided at the center of the fixing portion of the supporting means for fixing the vibrating means, and the vibrating means is fixed to the supporting means by resistance welding. Characterize.

A fourth invention is characterized in that the vibrating means is a prismatic tuning fork type vibrator.

[0009]

According to the present invention, when an angular velocity acts on a vibrating means that vibrates in a certain direction at a constant cycle about an axis orthogonal to the vibrating direction, the vibrating means is orthogonal to another vibrating direction different from the axial direction in which the angular velocity acts. The angular velocity is detected by detecting the Coriolis force generated in the direction by the detecting means. The first action is to make the vibrating means of the angular velocity sensor, the supporting means, the circuit board and the protecting means substantially parallel. To be installed.
(Claim 1) The second effect is that the vibrating means has a positioning means for fixing to the supporting means. (Claim 2) A third function is that an electrically high resistance portion is provided at the center of the fixed portion of the supporting means for fixing the vibrating means, and the vibrating means is welded to the supporting means by resistance welding. (Claim 3) A fourth action is that the vibrating means is a prismatic tuning fork type oscillator.
(Claim 4)

[0010]

The first effect is that the vibrating means, the supporting means, the circuit board and the protecting means are provided substantially parallel to each other, so that the angular velocity sensor can be easily assembled. In addition, since the protection means can have a shallow bottom, press processing can be performed for processing the protection means, and in addition, miniaturization of the angular velocity sensor can be realized. (Claim 1) The second effect is that since the vibrating means has the positioning means for fixing the vibrating means to the supporting means, the vibrating means can be easily positioned. (Claim 2) A third effect is that an electrical high resistance portion is provided in the center of the fixing portion of the supporting means for fixing the vibrating means, and the vibrating means can be welded to the supporting means by resistance welding. The welding robot can be used, and the angular velocity sensor can be assembled in a short time. (Claim 3) A fourth effect is that since the vibrating means is a prismatic tuning fork type oscillator, the natural frequency in the driving direction of the vibrator and the natural frequency in the direction in which the Coriolis force acts are set to appropriate values. As a result, the gain can be increased and the sensitivity of the angular velocity sensor can be increased. (Claim 4)

[0011]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 shows the configuration of the first embodiment of the present invention. The angular velocity sensor 100 includes a tuning fork vibrator 10 as a vibrating unit having a sound piece 11, a sound piece 12, and a neck portion 13 formed of a constant elastic alloy or the like, and a pedestal 4 made of a metal material.
0, the tuning fork vibrator 10 is approximately parallel to the pedestal 40, and
L-shaped support tool 3 that is supported so as to float on the pedestal 40
0, a driving element 21 as a driving means for vibrating the sound piece 11 and the sound piece 12 at a constant cycle, and a reference element 22 as a reference means for referring to the vibration state of the sound piece 11 and the sound piece 12. The sound element 11 and the sound element 12 are composed of a detection element 23 as a detection means for detecting the Coriolis force generated when an angular velocity acts. The support tool 30 and the pedestal 40 constitute a support means.

Side portion 11 of tuning piece 11 of tuning fork type vibrator 10.
The driving element 21 and the reference element 22 are fixed to the a by an adhesive agent, and the driving element 24 and the reference element 25 are similarly attached to the side surface portion 12a of the other sound piece 12 by an adhesive agent. It is fixed in. Further, the detection elements 23, 2 are provided on the upper surface portions 11b, 12b of the sound piece 11 and the sound piece 12, respectively.
6 is fixed with an adhesive.

The principle of angular velocity detection according to the present invention will be described. It is assumed that x, y, z, and o in the figure are three-axis orthogonal coordinate systems, and the pedestal 40 is provided parallel to the xz plane. When an AC voltage having a frequency matching the natural frequency of the tuning fork vibrator 10 is applied to the driving elements 21 and 24, x
The tuning fork vibrator 10 vibrates symmetrically in the axial direction. At this time,
When an angular velocity ω is applied to the tuning fork vibrator 10 around the z axis, y
A symmetrical Coriolis force is generated in the sound piece 11 and the sound piece 12 in the axial direction, and the Coriolis force is detected by the detection elements 23 and 26, and the angular velocity ω is obtained through appropriate circuit processing.

With the above structure, the present invention provides a tuning fork type vibrator 1
0 and the pedestal 40 can support the tuning fork type vibrator 10 without requiring machining such as drilling.
The workability and the assembling property of are improved. Further, since the height of the angular velocity sensor 100 can be made lower than that of the pedestal 40, the angular velocity sensor 100 can be downsized.
Furthermore, since the case that protects the tuning fork type vibrator 10 can be formed into a cup shape having a shallow bottom, the case can be easily processed by pressing.

Next, a second embodiment will be described. Figure 2
FIG. 6 is a structural diagram showing a configuration of a second embodiment of the present invention. The tuning fork vibrator 10 is substantially parallel to the base 40, and the base 4
The support member 31 that is provided so as to float at 0 is formed in an inverted v shape, and supports the tuning fork vibrator 10 on both side surfaces of the support member 31. As a method of fixing the tuning fork type vibrator 10 and the support tool 31, various methods such as screw tightening and welding can be applied.

With the above structure, since the tuning fork type vibrator 10 and the support 31 are fixed at two places, they can be fixed more firmly than in the first embodiment. Further, since the support 31 and the pedestal 40 are fixed at two places, stable assembly can be performed and more firmly fixed.

A third embodiment will be described. FIG. 3 is a structural diagram showing the configuration of the third embodiment. In this embodiment, by providing the hole 33 at the top of the inverted v-shaped support 32, a resistance welding method such as spot welding can be applied and cost-effective mass production is possible. .

FIG. 4 shows the welding current when spot welding is performed on the supporting portions 34 and 35 when the support member 32 is not provided with the hole 33 (a) and when the support 33 is provided with the hole 33 (b). This is shown by the dotted arrow. When the support member 32 is not provided with the hole 33, a considerable part of the welding current flows through the support device 32 in the direction of the dotted line arrow as shown in FIG.
There is a problem that a good melting due to a welding current does not occur between the No. 2 and the tuning fork vibrator 10 and sufficient holding of the tuning fork vibrator 10 cannot be obtained.

On the other hand, when the support member 32 is provided with the hole 33, the resistance in the vicinity of the hole 33 has a high resistance, so that the welding current is less likely to flow through the support 32 when spot welding is performed. As a result, the welding current flows along the path shown by the dotted arrow in FIG.
Good welding occurs due to the welding current, and the sufficient holding of the tuning fork vibrator 10 can be obtained. In the second embodiment, as an example for preventing the welding current from wrapping around, the case where the hole 33 is provided at the top of the support 32 is shown, but the top of the support 32 is constricted or thinned. Other means may be used as long as it is a means for preventing the welding current from flowing around.

In this embodiment, a prismatic tuning fork type oscillator is used as the tuning fork type oscillator 10. However, the orthogonal type tuning fork type oscillator described in JP-A-4-296618 may be used. By the way, in the prismatic tuning fork type vibrator, the resonance magnification of the prismatic tuning fork is used in order to effectively obtain the sensitivity for detecting the Coriolis force. In the case of this prismatic tuning fork type vibrator, more effective effects were obtained in the present embodiment, so that it will be described below. First, the resonance magnification β of the prismatic tuning fork vibrator 10 will be described. FIG. 5 (a)
FIG. 3 is a schematic diagram showing the relationship between the vibrating directions of the sound pieces 11 and 12 of the prismatic tuning fork vibrator 10 and the coordinate system. F _D in the figure,
f _S represents the natural frequency at which the prismatic sound pieces 11 and 12 vibrate symmetrically in the x-axis direction, and the natural frequency at which they vibrate symmetrically in the y-axis direction. . Tuning pieces 11, 12 of the prismatic tuning fork vibrator 10
Is symmetric vibrated in the x-axis direction by the driving element 21, and z
When an angular velocity is applied about the axis, Coriolis force acts in the y-axis direction, and the prismatic sound pieces 11 and 12 bend symmetrically in the y-axis direction. If the resonance frequency β is expressed using the natural frequency f _{D in} the x-axis direction and the natural frequency f _S in the y-axis direction, it can be given by Equation 1.
The resonance magnification β is given by Equation 1 where Q _S is an amount indicating the degree of damping of vibration in the Coriolis force detection direction, that is, the y-axis direction.

[0021]

[Number 1] β = {(1 - (f D / f S) 2) 2 + ((f D / f S) / Q S) 2} -1/2 ... (1) where, Q _S is y This is defined by the equation 2 when the damping ratio in the y-axis direction is ζ, which indicates the amount of damping of vibration in the axial direction.

[0022]

(2) Q _S = 1 / (2ζ) (2)

Here, if the difference between the natural frequency f _D in the x-axis direction and the natural frequency f _{S in the} y-axis direction is Δf, the natural frequency f _{D in the} x-axis direction is expressed by the formula 3 Is defined in.

[Formula 3] f _D = f _S + Δf (3)

In formula 1, since Q _S usually takes a value of several hundreds or more, formula 4 is derived by expanding formula 1 using formula 3.

[Formula 4] β ≈ f _S / (2Δf) (4)

From Equation 4, when a force is applied in the y-axis direction,
That is, when Coriolis force is applied, if the values of the natural frequency f _D in the x-axis direction and the natural frequency f _{S in} the y-axis direction are selected in advance, the gain becomes large and The displacement is enlarged and the sensitivity is multiplied by β (see FIG. 5B). Therefore, it is understood that the sensitivity of the prismatic tuning fork vibrator 10 to the angular velocity using the resonance magnification β depends on the resonance magnification β, that is, the natural frequency f _D in the x-axis direction and the natural frequency f _S in the y-axis direction. Natural frequency f _D, f _S is affected by the support state of the prismatic tuning fork vibrator 10, but if the prismatic tuning fork vibrator 10 using this example was fixed, the natural frequency f _D, f There is an advantage that _S is stabilized and, for example, the natural frequencies f _D and f _S are stabilized even when the environmental temperature changes, so that the resonance magnification β, that is, the sensitivity characteristic is stabilized.

A fourth embodiment will be described. FIG. 6 is a structural diagram showing the configuration of the fourth embodiment. In the fourth embodiment, the alignment means 14 for facilitating the assembling with the pedestal 40 on the neck portion 13 which is the support portion of the tuning fork type vibrator 10.
Is a feature. In the present embodiment, the step structure is used as the alignment means 14, but the tuning fork vibrator 1
Other means such as a protrusion or a line-shaped mark may be used as long as the 0 and the pedestal 40 can be aligned with each other.

The alignment means 14 facilitates the assembling of the tuning fork type vibrator 10 and the pedestal 40, and has the effect of reducing variations in the supporting position of the tuning fork type vibrator 10. Further, since the variation in the supporting position of the tuning fork type vibrator 10 is reduced, the natural frequencies f _D and f _S are stabilized, and particularly when the prismatic tuning fork type vibrator is used, the resonance magnification β, that is, the sensitivity. Variation can be reduced and a stable effect can be obtained.

The fifth embodiment will be described. FIG. 7 is a structural diagram showing the configuration of the fifth embodiment. The fifth embodiment is
1 shows an example of an assembly of the angular velocity sensor 100. The tuning fork type oscillator 10 is fixed to the pedestal 40 via the support 30, and the case 50 for protecting the tuning fork type oscillator 10 is welded to the pedestal 40 all around by projection welding. Input / output signals from the piezoelectric element arranged in the tuning fork vibrator 10 are connected to the circuit board 52 via the terminal 51 formed of a hermetic terminal, and the circuit board 5 is connected.
After appropriate circuit processing is performed at 2, the data is input to and output from an external ECU (Electronic Control Unit) or the like through the connector 54. The circuit protection cover 53 is fixed to the base 40 by caulking.

Here, since the tuning fork type vibrator 10 is arranged such that its longitudinal direction is substantially parallel to the pedestal 40, the case 50 can have a shallow bottom shape. Therefore, since the case 50 can be easily processed by pressing, the cost of the angular velocity sensor can be reduced, and the size of the angular velocity sensor can be reduced.

A sixth embodiment will be described. FIG. 8 is a structural diagram showing the configuration of the sixth embodiment. The sixth embodiment is
As with the fifth embodiment, an embodiment of the assembly of the angular velocity sensor is shown. The tuning fork type vibrator 10 is a support 3
It is fixed to the base 40 by 0 (not shown). A copper wire is connected between the piezoelectric element arranged on the tuning fork vibrator 10 and the terminal 51 by soldering. The signal of the piezoelectric element is connected to a circuit board 52 via a terminal 51 and a copper wire, and the signal is subjected to appropriate circuit processing on the circuit board 52 and then input / output from a connector 54 to an external ECU or the like.

On the other hand, the tuning fork vibrator 10 fixed to the pedestal 40 is protected by a case 50 which is projection welded to the pedestal 40 all around. The pedestal 40 is fixed to the flange 60 by screwing through a vibration proof rubber 55. The circuit board 52 is fixed to the flange 60 by tightening screws with stud bolts 56, and the flange 6
The cover 53 fixed by welding to 0 protects it from the influence of EMI and the like.

In the sixth embodiment, since the tuning fork type vibrator 10 is held by the flange 60 via the vibration isolating rubber 55, the influence of external vibration can be reduced. Since the flange 60, the case 50, the pedestal 40, the circuit board 52, and the cover 53 are arranged in this order from the right in FIG.
5. The dead space due to the thickness of the connector 54 is reduced, and the angular velocity sensor 100 can be downsized. Further, since the cover 53, the circuit board 52, and the pedestal 40 have a shielding effect against external sound waves coming from the left direction in FIG. 8, it is possible to eliminate the influence of the external sound waves on the characteristics of the angular velocity sensor 100. Have merits. In addition,
The flange 60 has a function of blocking external sound waves from the right direction.

The seventh embodiment will be described. FIG. 9 (a)
[FIG. 8] is a structural diagram showing a configuration of a seventh embodiment. The neck portion 13 of the tuning fork type vibrator 10 is fixed to the support 30 by means such as welding, and the protrusions 40-1 and 40- provided on the pedestal 40.
The tuning fork type vibrator 10 is fixed to the pedestal 40 substantially in parallel with the supporting member 30 by fixing the supporting member 30 to the member 2 by means such as welding. Note that FIG. 9B shows the welded portion from the cross-sectional direction, and the x mark indicates the welded portion.

The eighth embodiment will be described. Figure 10
(A) is a structural diagram showing a configuration of an eighth embodiment. In the seventh embodiment, the support means by the support tool 30 is shown, but in the eighth embodiment, the support means is provided on the pedestal 40. The tuning fork vibrator 10 is fixed to the pedestal 40 by providing the pedestal 40 with the projection 40-3 and fixing the neck 13 to the projection 40-3 by means such as welding. In addition, FIG. 10 (b) shows the welded portion from the cross-sectional direction, and the x mark indicates the welded portion. With the configuration shown in FIG. 10, the angular velocity sensor 1
The structure of 00 can be further simplified.

The ninth embodiment will be described. Figure 11
FIG. 9A is a structural diagram showing the configuration of the ninth embodiment. The support member 38 is formed in an inverted V shape, and the neck portion 13 and the support member 38 are
Are fixed by welding or the like, and the support 38 and the pedestal 40 are fixed by welding or the like, so that the tuning fork vibrator 10 and the pedestal 40 are fixed. Note that FIG. 11 (b) shows the welded portion from the cross-sectional direction, and the cross indicates the welded portion. In this case, the tuning fork vibrator 10 can be positioned by aligning the end of the neck 13 and the end of the support 38.

[Brief description of drawings]

FIG. 1 is a structural diagram showing a configuration of a first embodiment according to the present invention.

FIG. 2 is a structural diagram showing a configuration of a second embodiment according to the present invention.

FIG. 3 is a structural diagram showing a configuration of a third embodiment according to the present invention.

FIG. 4 is a schematic diagram showing how a welding current flows when spot welding is performed on a supporting portion in the case where a hole is not provided in a support tool (a) and the case where a hole is provided (b).

5A and 5B are a schematic diagram showing a relation between a vibration direction of a prismatic tuning fork type oscillator and a coordinate system, and a schematic diagram showing a relation between a frequency and a resonance magnification of a prismatic tuning fork type oscillator.

FIG. 6 is a structural diagram showing a configuration of a fourth embodiment according to the present invention.

FIG. 7 is a structural diagram showing a configuration of a fifth embodiment according to the present invention.

FIG. 8 is a structural diagram showing the configuration of a sixth embodiment according to the present invention.

FIG. 9 is a structural view (a) showing a configuration of a seventh embodiment according to the present invention and a schematic view (b) showing a welded portion thereof.

FIG. 10 is a structural view (a) showing a configuration of an eighth embodiment according to the present invention and a schematic view (b) showing a welded portion thereof.

FIG. 11 is a structural view (a) showing a configuration of a ninth embodiment according to the present invention and a schematic view (b) showing a welded portion thereof.

[Explanation of symbols]

10 tuning fork type vibrator 11, 12 sound piece 11a, 12a sound piece side surface portion 11b sound piece upper surface portion 13 tuning fork neck portion 14 alignment means 21 drive element 22 reference element 23, 26 detection element 30 to 32, 38 support 33 Holes 34, 35 Supporting parts 36, 37 Fixing parts 40 Pedestals 40-1 to 40-3 Protrusions 50 Case 51 Terminal 52 Circuit board 53 Cover 54 Connector 55 Vibration-proof rubber 56 Stud bolt 60 Flange 100 Angular velocity sensor ω Angular velocity β Resonance Magnification ζ Damping ratio Q _S Amount that indicates the degree of vibration damping in the y-axis direction f _D x Natural frequency in the x-axis direction f _S y Natural frequency in the y-axis direction × Welding site

Claims (4)

[Claims] 1. An angular velocity sensor for detecting an angular velocity, comprising: a vibrating unit that vibrates in a constant direction at a constant cycle; a driving unit that vibrates the vibrating unit in a constant direction at a constant cycle; Detecting means for detecting the Coriolis force generated when the force acts, the supporting means for fixing the vibrating means, the driving means electrically driven, and the angular velocity from the Coriolis force detected by the detecting means. And a protection means for protecting the components of the angular velocity sensor such as the vibration means and the circuit board, and the vibration means, the support means, the circuit board and the protection means are provided substantially in parallel. Angular velocity sensor characterized in that. 2. The vibrating means has a positioning means for fixing the vibrating means to the supporting means.
Angular velocity sensor described in. 3. An electric high resistance portion is provided at the center of a fixed portion of the supporting means for fixing the vibrating means, and the vibrating means is fixed to the supporting means by resistance welding. The angular velocity sensor according to claim 1. 4. The angular velocity sensor according to claim 1, wherein the vibrating means is a prismatic tuning fork type oscillator.