JPH0812202B2 - Accelerometer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration measuring device that applies acceleration to an acceleration sensor and checks the performance of the acceleration sensor from the output signal thereof.

2. Description of the Related Art Conventionally, as shown in FIG. 2, this type of acceleration measuring device includes a rotating arm 33 that revolves around a center axis 31 in the direction of an arrow 32, and a radius r from the center axis 31 of the rotating arm 33.
And a turntable 35 that is attached to the end of the rotary table and rotates in the direction of arrow 34. An acceleration sensor 36 as a specimen is mounted on the rotary table 35, and a rotating arm 33 is provided.
The acceleration is determined by the revolution speed of the rotary table 35
The applied frequency is determined by the rotation of the motor, and the magnitude of the acceleration at a certain applied frequency is measured.
Assuming that the acceleration at this time is α, the applied frequency f and the radius r, there is a relationship α = r (2πf) ² .

As another device for measuring acceleration, there is a simple pendulum system utilizing gravitational acceleration g as shown in FIG. In this device, a lever 42 having a length 1 which is a swinging end pendulum having a base end portion swingably fixed to a top plate 41,
And a holder 43 fixed to the tip. The acceleration sensor 44, which is the sample, is set in the holder 43 and the arrow
The acceleration generated by alternately swinging in the directions of 45 and 46 is measured. At this time, the relationship between the gravitational acceleration g, the lever length l, and the applied frequency (also referred to as period) T is become that way. The relationship among the acceleration α, the gravitational acceleration g, the lever length 1 and the head S is α = − (g / l) S.

Problems to be Solved by the Invention However, the conventional acceleration measuring device has the following problems.

First, in the apparatus shown in FIG. 2, since the rotation speed and the revolution speed can be independently varied, there is an advantage that the acceleration α can be independently varied for one applied frequency f. Because of the two types, mechanical vibration noise is easily generated, and electric noise is easily generated due to the presence of the electric sliding contact portion. Further, the size of the apparatus tends to be large and expensive.

Next, in the apparatus shown in FIG. 3, in order to cause the acceleration sensor 44, which is a specimen, to swing at a low frequency or to increase the applied frequency T, the above equation is used. Therefore, the lever length l must be increased, and the size of the apparatus increases. In addition, the acceleration α tends to vary depending on how the lever 42 is released, and it is difficult to always keep the posture of the acceleration sensor 44, which is the sample, constant.

Furthermore, it is extremely difficult for any of the above-mentioned acceleration measuring devices to measure in the ultra-low frequency region of 1 Hz or less.

The present invention is to solve such a conventional problem, the applied frequency is an ultra-low frequency region of 1 Hz or less,
Moreover, it is an object of the present invention to provide an inexpensive and compact acceleration measuring device capable of measuring acceleration at low acceleration with high accuracy.

Means for Solving the Problems In order to achieve the above object, the present invention configures a link mechanism by combining a cam, a lever, and a wire, and selects a contour curve of the cam to attach the test piece to the wire. By obtaining the movement characteristics of the weight to be held,
It is designed to measure the acceleration in the ultra low frequency and low acceleration region of 1Hz or less with high accuracy.

Action The present invention has the following effects due to the above configuration. That is, the motion of the weight on which the test piece is set is set in consideration of the motion characteristics of the link mechanism so that it becomes a cycloid curve, and the acceleration is applied to the test piece by the suspension method. By doing so, it is possible to realize speed measurement in the ultra-low frequency region of 1 Hz or less and the low acceleration region of 0.1 G or less without transmitting vibration from the outside without increasing the size of the device.

Embodiment FIG. 1 shows the structure of an embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a cam, which is fixed by a key 3 to an output shaft 2 that transmits the rotation of a DC motor (not shown) via a speed reducer (not shown). Reference numeral 4 denotes a wire, one end of which is attached to a cam follower 13 provided at one end of a lever 12 which swings in the directions of arrows a and b in FIG. Weight 7 to prevent slack and to stabilize movement
Is provided. Reference numeral 5 is a guide roller for guiding the wire 4 and preventing the weight 7 from rolling. 6
Is a test acceleration sensor, and is attached to the weight 7 so as to detect vertical acceleration. In addition, the contour curve of the outer peripheral surface of the cam 1 allows the movement characteristics such as a single chord curve or a cycloid curve to be accurately realized with respect to the reciprocating movement of the weight 7 in the direction of the arrow 8 in FIG.
It was created after analyzing and considering the movement of the lever 12.

Next, the operation of the above embodiment will be described. In response to an input command from a DC controller (not shown), the cam 1 rotates about the output shaft 2 via the DC motor and the speed reducer, and the lever 12 moves about the fulcrum 11 in the directions of arrows a and b. The swing motion is performed according to the contour curve of the cam 1. As a result, the weight 7 and the test acceleration sensor 6 provided there through the wire 4 reciprocate linearly in the direction of the arrow 8. The motion characteristic of this reciprocating linear motion becomes a single chord curve, a cycloid curve, etc. according to the contour curve of the cam 1 as described above. Therefore, the sample acceleration sensor 6 outputs an output according to the magnitude of the acceleration applied by this movement, and this output value is measured by an output device such as an oscilloscope or a pen recorder. The applied frequency can be changed by changing the rotation speed of the DC motor.

Since the maximum acceleration of the cycloid curve is about 1.3 times that of the single-string curve, in order to give the same acceleration to the test acceleration sensor 6, the lever is more than the case of the single-string curve.
The swing width of 12 requires a small stroke.

Therefore, according to the above-described embodiment, the test acceleration sensor 6 has a structure in which it is suspended by the wire 4 via the weight 7, and the wire 4 is guided by the guide roller 5, so that the cam 1 and the lever 12 are provided. Since it is difficult to transmit the vibrations from and the sliding portion does not exist, it is possible to realize a motion having a smooth single string or a cycloid curve with very little vibration, for the acceleration sensor 6 under test. It has an effect that vibration noise is less transmitted, and acceleration in a low acceleration region of 1 Hz or less and in a low acceleration region can be measured with high accuracy and reliability.

Although the wire is attached to the cam follower 13 provided on the lever 12 in this embodiment, a sturdy thread may be used for this purpose.

As is apparent from the above embodiment, the present invention has a cam having a cam curve for obtaining a predetermined motion characteristic, a lever driven by this cam to perform a swing motion, and suspended from the lever. Wire and a reciprocating linear motion that is attached to the lower end of the wire, and has a weight that holds the sample, so there is little transmission of vibration noise from the outside, in the ultra-low frequency range of 1 Hz or less, Moreover, acceleration at low acceleration can be measured with high accuracy and reliability,
Moreover, there is an effect that an inexpensive and compact acceleration measuring device can be realized.

[Brief description of drawings]

FIG. 1 is a front view of an acceleration measuring device according to an embodiment of the present invention, FIG. 2 is a front view of a conventional acceleration measuring device, and FIG. 3 is a front view of another conventional acceleration measuring device. 1 ... Cam, 2 ... Output shaft, 3 ... Key, 4 ... Wire, 5 ... Guide roller, 6 ... Test acceleration sensor,
7 ... weight, 11 ... fulcrum, 12 ... lever, 13 ... cam follower.

Claims (1)

[Claims] 1. A cam having a cam curve for obtaining a predetermined motion characteristic, a motor for rotationally driving the cam, a lever driven by the cam for rocking motion, and attached to one end of the lever. An acceleration measuring device comprising: a wire; a guide roller for guiding the wire; and a weight attached to a lower end of the wire for reciprocating in a vertical direction and holding an acceleration sensor as a sample.