JPH0776775B2 - Acceleration generator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration generator used for acceleration measurement such as an acceleration sensor.

2. Description of the Related Art Conventionally, as shown in FIG. 3, an acceleration generator of this type has a rotating arm 33 revolving around a center shaft 31 in a direction of an arrow 32 and a radius r from the center shaft 31 of the rotating arm 33.
And a rotary table 35 that is attached to the end of the rotary table 35 and rotates in the direction of arrow 34. An acceleration sensor 36, which is a sample, is mounted on the rotary table 35, and the rotary arm 33
The rotation speed of the rotary table 35 determines the acceleration.
The applied frequency is determined by the rotation of the, and the magnitude of acceleration at a given applied frequency is measured.
If the acceleration at this time is α, the applied frequency f and the radius r, there is a relationship of α = r (2πf) ² .

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

However, the above-described conventional acceleration generator has the following problems.

First, in the device shown in FIG. 3, since the rotation speed and the revolution speed can be changed independently, there is an advantage that the acceleration α can be changed independently for one applied frequency f. There is a problem that mechanical vibration noise is liable to occur due to the existence of the two types, and electric noise is likely to occur due to the presence of the electric sliding contact portion. Further, there is a problem that the device becomes large in size and expensive.

Next, in the apparatus shown in FIG. 4, in order to swing the sample acceleration sensor 44 at a low frequency or to increase the applied frequency T, Therefore, the lever length 1 has to be increased, which causes a problem of increasing the size of the device. Further, there are problems that the acceleration α is likely to vary depending on how the lever 42 is released, and that it is difficult to always keep the posture of the sample acceleration sensor 44 constant.

Further, all of the above-described acceleration generators have a problem that it is extremely difficult to measure the acceleration in the ultralow frequency region of 1 Hz or less.

The present invention is to solve such conventional problems, the applied frequency is 1Hz or less in the ultra-low frequency region,
Moreover, it is an object of the present invention to provide an inexpensive and compact acceleration measuring device that can generate its own acceleration with high accuracy.

Means for Solving the Problems In order to achieve the above object, the present invention forms a link mechanism by combining a rotating cam, a lever, and an air slider, and appropriately selects a cam curve of the cam as an operating characteristic of the air slider. Obtained by doing, especially at ultra-low frequencies below 1 Hz,
The acceleration is generated in a low acceleration region and the acceleration can be measured with high accuracy.

Action The present invention has the following effects due to the above configuration. That is, by setting the movement of the air slider on which the specimen is set, considering the movement characteristics of the link lever mechanism so that the cam curve that maximizes the maximum speed, for example, a cycloid curve, is set, Acceleration in the low frequency region can be generated without increasing the size of the device and can be measured by the acceleration sensor. In addition, by using a low-friction, low-vibration, smooth moving body called an air slider, high-accuracy acceleration measurement is possible with little noise even at low acceleration of 0.1 G or less.

Embodiment FIG. 1 is a plan view showing the construction of an embodiment of the present invention, and FIG. 2 is a front view thereof. In FIGS. 1 and 2, 1
Is a DC motor, the power band of which is taken out from the output shaft 3 via the reduction gear unit 2. 3A is a housing for fixing a bearing for receiving the output shaft 3. Reference numeral 4 denotes a cam, which is fixed to the output shaft 3 by a key 5. Reference numeral 6 is an air slider movable portion, and reference numeral 7 is a lever that swings around a fulcrum shaft 8 to reciprocate the air slider movable portion 6.
The fulcrum shaft 8 is fixed to the base 9. The cam curve of the outer peripheral surface of the cam 4 indicates that the movement of the air slider moving part 6 is the lever 7
It is formed to have a cycloidal curve in consideration of the movement of. On the top of the lever 7, the cam follower 10,1
1,12,13 are rotatably fixed. Reference numeral 14 is a guide groove formed on the bottom surface of the air slider movable portion 6, and one of the cam followers 10, 11, 12, and 13 is fitted and guided therein. In the figure, a cam follower 13 at a position farthest from the fulcrum shaft 8 is fitted in a guide groove 14 so as to be rollable. Reference numeral 15 denotes an air slider guide shaft, both ends 15a and 15b of which are fixed to the sub-base 16. Numerals 17 and 18 are holes provided in the sub-base 16 to allow the movement of the air slider movable portion 6. Reference numeral 19 is a pressing plate for pressing the cam 4 against the bearing housing 3A, and 20 is a spring for constantly pressing the follower cam follower 21 rotatably fixed to the lower portion of the lever 7 against the outer peripheral surface of the cam 4. 22 is a pedestal that supports the entire apparatus. An anti-vibration rubber 23 is attached to the bottom of the pedestal 22 in order to prevent intrusion of external vibration. The air slider guide shaft 15 is also vibrationally insulated from the sub-base 16 by a vibration-proof rubber 24. Reference numeral 25 denotes a specimen holder on the upper surface of the air slider movable portion 6, on which an acceleration sensor as a specimen is set. The holding mechanism for setting is not shown. Reference numeral 26 is a position detection sensor for detecting the fixed position of the cam 4, and 27 and 28 are a DC motor controller and a DC motor driver fixed to the frame 22, respectively.

Next, the operation of the above embodiment will be described. First, when the DC motor 1 is rotated by the input command from the DC motor controller 27 and the cam 4 is rotated, the lever 7 swings around the fulcrum shaft 8 in the directions of arrows a and b along the cam curve. To do. As a result, the air slider movable portion 6 reciprocates linearly in the directions of arrows A and B.

The reciprocating motion characteristic of the air slider movable portion 6 becomes a cycloid curve following the cam curve of the cam 4, and the cycloid curve motion is performed once in each stroke of the reciprocating motion. Therefore, the test acceleration sensor set in the holding portion 25 on the upper surface of the air slider movable portion 6 performs one reciprocating cycloid curve movement by one rotation of the cam 4, that is, a total of two cycloid movements. Since the output is output according to the magnitude of the acceleration generated by the motion, the output value of the test acceleration sensor corresponding to the applied acceleration is measured by an output device such as an oscilloscope or a pen recorder. Applied frequency is DC motor 1
It is decided by changing the rotation speed of.

The maximum acceleration of the cycloid curve is about
Since it is 1.3 times, a smaller stroke is required to give the same acceleration to the test acceleration sensor than in the case of a single-string curve.

Further, since the test acceleration sensor is held by the air slider, it is possible to realize smooth motion with less vibration, and to block the vibration from the movable part such as the rotating part from being transmitted to the test acceleration sensor. Since it is possible to further reduce frictional resistance during reciprocating motion as much as possible,
It is possible to make the acceleration sensor more faithfully perform the cycloid curve movement.

Further, both ends 15a and 15b of the air slider guide shaft 15 are attached to different positions, and the cam followers 10, 11 and 12 of the lever 7 are fitted into the guide grooves 14 of the air slider movable portion 6 so as to be provided. The stroke of the air slider movable portion 6 can be changed according to the output value range of the acceleration sensor to be tested.

As described above, according to the above-described embodiment, since the cycloid curve having the large maximum acceleration is used as the cam curve,
Even in an ultra-low frequency region of 1 Hz or less, acceleration can be generated without increasing the stroke of the device, and the acceleration sensor can measure this. Further, since the acceleration sensor for test is held by the holding portion 25 on the upper surface of the air slider movable portion 6, and the pedestal 22 and the air slider guide shaft 15 are supported by the vibration proof rubbers 23 and 24, the low acceleration of 0.1 G or less is achieved. However, there is an effect that acceleration with less noise can be generated and highly accurate acceleration can be measured.

The motion curve given to the test acceleration sensor, that is, the cam curve of the cam 4 can be variously changed according to the type of the acceleration sensor as the test piece or the required measurement value.

EFFECTS OF THE INVENTION As apparent from the above-described embodiment, the present invention holds a cam having a cam curve for obtaining a predetermined motion characteristic, a lever swung by rotationally driving the cam, and a specimen. Since it is equipped with an air slider that is reciprocated by this lever, the acceleration sensor can measure the acceleration at low acceleration in the ultra-low frequency range with high accuracy and reliability, and it is inexpensive and compact. This has the effect of realizing a different acceleration generator.

[Brief description of drawings]

FIG. 1 is a plan view of an acceleration generator according to an embodiment of the present invention, FIG. 2 is a front view of the same, FIG. 3 is a schematic configuration diagram of a conventional acceleration generator, and FIG. It is a schematic block diagram of an acceleration generator. 1 ... DC motor, 2 ... deceleration unit, 3 ... output shaft,
4 ... Cam, 5 ... key, 6 ... Air slider moving part,
7 ... Lever, 8 ... fulcrum shaft, 9 ... base, 10,11,1
2,13, ... Cam follower, 14 ... Guide groove, 15 ... Air slider guide shaft, 15a, 15b ... Air slider guide shaft end, 16 ... Sub base, 17,18 ... Air slider moving part Holes, 19 …… Pressing plate, 20 …… Spring, 21
...... Following cam follower, 22 …… Stand, 23,24 …… Anti-vibration rubber, 25 …… Sample holder, 26 …… Position detection sensor, 27 ……
… DC motor controller, 28 …… DC motor driver.

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 a reciprocating drive by the lever. An acceleration generator including an air slider that holds a sample while moving.