JPH10148641A - Angular acceleration sensor - Google Patents

Abstract

[PROBLEMS] To provide a highly responsive and highly reliable angular acceleration sensor which has high sensitivity, has excellent environmental resistance to dust and the like, and can detect high-frequency angular acceleration. An angular acceleration sensor for detecting an angular acceleration of a rotating body includes a rotating shaft supported by a bearing fitted to a housing and connected coaxially with the rotating body so as to rotate integrally with the rotating body. An annular weight 41 disposed outside of 3
A rib 43 for connecting the rotating shaft 3 to the weight 41; a magnetostrictive film 44 having a reverse magnetostrictive effect on the surface of the rib 43; , 6 are wound, and the rib 43 is inclined toward the weight 41 so as to surround the rotating shaft 3 as viewed from the shaft end of the rotating shaft 3. It is arranged. With such a configuration, an angular acceleration sensor having high sensitivity, excellent environmental resistance, and capable of detecting high-frequency angular acceleration can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular acceleration sensor for detecting angular acceleration of a rotating body such as a motor shaft in a non-contact state.

[0002]

2. Description of the Related Art As one of conventional angular acceleration sensors, there has been proposed an angular acceleration detecting device which has a small installation space and also has a compact configuration and also serves as an angle detecting device (for example, Japanese Patent Application Laid-Open No. H10-157, 1988).
JP-A-6-337212). Conventionally, a detecting device to which this angular acceleration sensor is applied has a structure as shown in a longitudinal sectional view of FIG. 4 and plan views of FIGS. FIG.
FIG. 6 is a plan view showing the shape of a rigid disk, and FIG. 6 is a plan view showing the shape of an elastic disk. In the figure, the detection device has a thin cylindrical housing 1, and a rotating shaft 3 to be measured is rotatably penetrated through a center of the housing 1 via a bearing 2, and the rotation is located in the housing 1. Two disks 12 and 13 are fixed to the outer periphery of the shaft 3 in a state where the disks 12 and 13 face each other. One disk 12 is a rigid disk, and a first slit row 121 and a second slit row 122 are formed concentrically on the outside thereof in the circumferential direction. The first slit row 121 is formed of radially extending slits formed at a constant pitch. The other disk 13 is an elastic disk having a structure to be described later, is slightly smaller than the disk 12, and has a third slit row directed in the circumferential direction at a position facing the first slit row 121 on the outer peripheral side thereof. 13
1 is formed. Of these, the third slit row 131
Are supported by circumferentially elastically deformable ribs 134, 135, 136 between the outer annular portion 132 and the inner annular portion 133 forming a boss for attaching the rotating body. In addition, three sets of optical sensors 1 are sandwiched between the slit forming positions of the first and second disks from both sides.
4, 15, and 16 are arranged. Of these optical sensors, 14 and 15 are for detecting angular acceleration, and the light emitting diodes 141 and 151 and the semiconductor position detector 14 for receiving light are used.
2, 152. Also, the remaining sensor 1
Reference numeral 6 denotes an element for detecting an angle, in which the light emitting element 161 and the light receiving element 162 are arranged so as to sandwich the second slit row. In this example, the sensor 16 is arranged in the radial direction of the sensor 14. It is. In such a configuration, when the rotating shaft 3 starts rotating or when the rotation speed changes, the slit row 131 on the elastic disk 13 side moves in the circumferential direction with respect to the slit row 121 on the other rigid disk 12 side. Deviate. That is, the annular portion 13 formed on the elastic disc 13
Due to the inertial force of 2, its spring portions 134, 135, 1
36 is elastically deformed in the circumferential direction.
Also shifts in the circumferential direction accordingly. As a result, the relative movement amount in the radial direction of the intersection (light passing portion) formed between the slit row 131 and the slit row 121 is determined by the sensor 14,
The rotational angular acceleration of the rotating shaft 3 can be measured based on the relative movement amount. Further, the rotation angle can be detected by detecting the second slit row 122 of the rigid disk by the sensor 16.

[0003]

In the prior art, however, the relative displacement of the rigid disk and the elastic disk fixed to the rotating shaft with the rotation of the slit array formed on each disk is detected by a sensor, and the angular displacement is detected by a sensor. In the configuration in which the acceleration is obtained, the slit row on the elastic disk side has a problem that the position shift amount due to the mechanical deformation is detected and thus the sensitivity is low, and the optical measurement has poor environmental resistance against dust and the like. Also, the rib made of spring material on the elastic disk side connects the annular weight and the boss and functions as a member that can be elastically deformed. I couldn't. Therefore, the present invention has high sensitivity, excellent environmental resistance to dust and the like, and can increase the natural frequency without reducing the shape of the rib portion, and can detect high-frequency angular acceleration. It is an object of the present invention to provide a highly responsive and highly reliable angular acceleration sensor that can be used.

[0004]

Means for Solving the Problems To solve the above problems, the angular acceleration sensor of the present invention is as follows. (1) In an angular acceleration sensor that detects angular acceleration caused by rotation of a rotating body, a housing, a bearing fitted to the housing, and a coaxial state supported by the bearing and rotated integrally with the rotating body. A rotating shaft connected to the
An annular weight portion disposed outside the rotation shaft, a plurality of ribs fixed to the rotation shaft and connecting the weight portion, and a magnetostrictive body having an inverse magnetostrictive effect on at least a part of the surface of the rib And excitation detecting means disposed in the magnetostrictive body via a gap. (2) The rib is made of a non-magnetic material, and the magnetostrictive body has a film formed on the surface of the rib. (3) The rib is disposed so as to be inclined in the circumferential direction from the rotation shaft toward the weight portion side as viewed from the shaft end of the rotation shaft. (4) a plurality of the magnetic detection means in the circumferential direction of the rib,
It is arranged.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view of an angular acceleration detecting device according to an embodiment of the present invention, and FIG.
And FIG. 3 is a circuit diagram of a detection system of the detection device. In the figure, reference numerals 1 to 3 denote the same constituent elements as those of the conventional example, and are denoted by the same reference numerals. A rotating shaft 3 to be measured is rotatably penetrated through a center of a housing 1 via a bearing 2. Reference numeral 4 denotes a disk fixed to the outer periphery of the rotating shaft 3 located in the housing 1, and 41 denotes a disk 4.
, An annular weight portion provided on the outside, 42 is an annular boss portion for fixing the disk 4 to the rotating shaft 3, 43 is a rib connecting the weight portion 41 and the boss portion 42, The disk 4 is constituted by a weight 41, an annular boss 42 and a rib 43. In order to detect the direction of the angular acceleration, the rib 43 is disposed so as to be inclined in the circumferential direction from the rotating shaft 3 toward the weight 41 when viewed from the shaft end of the rotating shaft 3. In addition, since the weight 41 is supported by the rib 43, the weight 41 generated with the rotation is generated.
Due to the inertia force, the rotational movement of the weight 41 is delayed with respect to the rotational movement of the rotating shaft 3 and the boss 42, and the stress concentrates on the rib 43. As described above, the outer weight portion 41 functions as a weight portion for causing the rib 43 to be distorted by stress due to the inertial force. Further, the rib 43 may be a magnetostrictive body having an inverse magnetostrictive effect on at least a part of its surface, and the rib 43 may be made of a non-magnetic material and a magnetostrictive film having an inverse magnetostrictive effect may be formed on its surface. A magnetostrictive body may be used. In this embodiment, a magnetostrictive film 44 is formed on the surface of the rib 43. On the outer periphery of the magnetostrictive film 44, U-shaped iron cores 5 and 6 for magnetic detection are disposed opposite to each other at a position deviated by 180 ° so as to sandwich the magnetostrictive films 44 on both sides of the rib 43 via a gap. Excitation coils 7 and 8 are provided on the sides of the weights 41 of the disk 4 in 5 and 6, respectively. The exciting coil is connected to an AC power supply 9 of several kHz to several hundred kHz. By exciting the exciting coils 7 and 8, a magnetic circuit having the magnetostrictive film 44 of the rib 43 as a part of the magnetic path is formed. The exciting coils 7 and 8 are connected to load resistors 10 and 11 on the signal processing circuit, respectively, and
7 is formed.

Next, the operation will be described. In the angular acceleration sensor shown in the present embodiment configured as described above, the rotation shaft 3 starts rotating or the rotation speed changes, and a
When an angular acceleration occurs in the direction of, a tensile stress acts on the rib 43 due to the inertial force of the weight 41. As a result, the magnetic permeability of the magnetostrictive film 44 increases (or decreases). Conversely, when angular acceleration occurs in the direction of b in FIG.
Compressive stress acts on the weight 41, and the magnetic permeability of the magnetostrictive film 44 decreases (or increases). Therefore, a change in the magnetic permeability of the magnetostrictive film 44 based on these stresses of the rotating rib 43 is detected as an impedance change in the two exciting coils 7 and 8, and the difference between the terminal voltages of the two exciting coils is determined by the bridge voltage of the bridge circuit 17. V ₁ and is detected by differential detection means 19 including a differential amplifier 18. By the bridge voltages V ₁ of the AC to the rectifying and smoothing, the sensor output proportional to angular acceleration can be obtained as the direct-current voltage V _2. By the above means, an inertial force is generated in the weight portion 41 by the angular acceleration, and a distortion is generated in the rib 43 due to the stress. This distortion causes the magnetostrictive film 44 to change its magnetic permeability due to the inverse magnetostrictive effect. Therefore, the change in magnetic permeability can be detected as a change in the impedance of the exciting coils 7 and 8, and the angular acceleration can be measured.

[0007]

As described above, according to the present invention, since the amount of distortion of the rib caused by the angular acceleration is magnetically measured, the sensitivity is high and the environment resistance to dust and the like is excellent. Further, since the rib distortion is detected, it is not necessary to make the rib shape thin, the natural frequency can be increased, and a highly responsive and highly reliable angular sensor capable of detecting high frequency angular acceleration. There is an effect of obtaining an acceleration sensor.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an angular acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a plan view of the angular acceleration sensor taken along the line AA ′ in FIG.

FIG. 3 is a circuit diagram showing a detection system of the device of FIG.

FIG. 4 is a longitudinal sectional view of a conventional angular acceleration sensor.

FIG. 5 is a plan view showing the shape of a rigid disk in the apparatus of FIG.

FIG. 6 is a plan view showing the shape of an elastic disk in the device of FIG.

[Explanation of symbols]

1: Housing, 2: Bearing 3: Rotating shaft, 4: Disk 41: Weight part, 42: Boss part 43: Rib, 44: Magnetostrictive film 5, 6: Iron core, 7, 8: Exciting coil 9: AC power supply, 10, 11: load resistance 17: bridge circuit, 18: differential amplifier 19: differential detection means a. b: rotating shaft rotation direction V ₁ of the: bridge voltage V _2: angular acceleration sensor output (DC voltage)

Claims (4)

[Claims] 1. An angular acceleration sensor for detecting angular acceleration caused by rotation of a rotating body, comprising: a housing; a bearing fitted to the housing; and a bearing supported by the bearing and integrally rotating with the rotating body. A rotating shaft connected in a coaxial state, an annular weight portion disposed outside the rotating shaft, a plurality of ribs fixed to the rotating shaft and connecting the weight portion, and at least a surface of the rib An angular acceleration sensor comprising: a magnetostrictive body partially having an inverse magnetostrictive effect; and excitation detecting means disposed in the magnetostrictive body via a gap. 2. The angular acceleration sensor according to claim 1, wherein the rib is made of a non-magnetic material, and the magnetostrictive body has a film formed on a surface of the rib. 3. The corner according to claim 1, wherein the rib is disposed so as to be inclined in a circumferential direction from the rotation shaft toward the weight portion side when viewed from a shaft end side of the rotation shaft. Acceleration sensor. 4. The angular acceleration sensor according to claim 1, wherein a plurality of said magnetic detecting means are provided in a circumferential direction of said rib.