JPH0246345A - Oscillation generator - Google Patents

Abstract

PURPOSE:To make the temporal change of an oscillating angle, angular velocity and angular acceleration sine wave form by having the cam surface of a rotation driving shaft formed such that the center of a cam follower is made a shifting locus shown on the polar coordinate by the specified relational expression having the rotation center as an origin. CONSTITUTION:The cam surface 5a of a cam 5 provided at a rotation drive shaft 4 is formed such that the center O2 of a cam follower 3 is made a shifting locus shown on the polar coordinate by the relational expression of an expres sion I having the rotation center O1 as an origin, provided that R: the distance from the reference line orthogonal to the rotation axis of the cam 5, psi : the angle from the reference line orthogonal to the rotation axis of the cam 5, Ra: distance between the oscillating shaft line of the oscillating shaft 2 and the rotation shaft line of a rotation driving shaft 4, theta : the oscillation angle of the oscillating shaft 2, alpha : the rotating angle of the cam 5. As a result, the temporal angle change of the oscillating shaft 2 is made sine wave form so that the angular velocity as well as the angular acceleration can be made sine wave form.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vibration generating device, and particularly to a vibration generating device suitable for use in a vibration tester.

[Prior Art] Conventionally, as an example of a structure of a 7.1 motion generator, one using a crank mechanism or a hydraulic actuator has been proposed.

The former swing generator has one end of the connecting rod rotatably attached to the crankshaft at a position radially away from its rotation center, and the other end of the connecting rod connected to the swing center of the swing shaft. It has a configuration in which it is rotatably mounted at a position spaced apart in the radial direction from
Furthermore, the reciprocating motion of the connecting rod is converted into the rocking motion of the rocking shaft.

The latter converts the reciprocating motion of a piston of a hydraulic actuator into a swinging motion of a swinging shaft by means of a swinging arm attached to the swinging shaft orthogonally to the swinging axis.

[Problems to be Solved by the Invention] By the way, in the rocking generator having the above-described configuration, when changing the rocking angle of the rocking shaft and changing the angular velocity and angular acceleration accordingly, in the former case, the connecting rod This is done by adjusting the length or, in the latter case, by adjusting the stroke of the piston, but considering the inertial mass of the moving part, the adjustment range is extremely narrow, and the change pattern of angular velocity and angular acceleration is not correct. Only a sinusoidal waveform can be obtained.

Therefore, it is desired to have a configuration that allows these change patterns to be changed as appropriate.

The present invention aims to solve such problems.

[Means for Solving the Problems] The present invention aims to provide a vibration generating device that can effectively solve the above-mentioned problems.
cam followers provided on the swing shaft at two positions spaced apart in the swing radial direction from the swing center and spaced apart in the swing direction; and cam followers provided along the swing shaft on both sides of the two cam followers. a pair of rotary drive shafts, and a cam having a cam surface that is integrally provided with each of these rotary drive shafts and that allows each of the cam followers to moveably come into contact with the cam, the cam surface of each of the cams With the center as the origin, the center of the Fuuki cam follower is as shown in (1) to (4) below.
It is characterized by being shaped so as to have a movement locus represented by polar coordinates according to the relational expression.

R= ((RaX Sinθ)”+ (La −RaX
Case) f) 171. ,,■ψ=π−jan(A/
B)+α...■A=Ra-
3inθ...■B=
La-1ia-Case
・-■ However, R: Distance ψ from the center of the cam to the center of the cam follower brought into contact with the cam surface; Angle Ra from the reference line perpendicular to the rotational axis of the cam;
Distance La between the swing axis of the swing shaft and the rotation axis of the cam follower: Distance θ between the swing axis of the swing shaft and the rotation axis of the rotary drive shaft: Swing angle α of the swing shaft; Rotation angle of the cam [Function] According to the present invention, by changing the profile of the cam surface of the cam with which the cam follower is movably brought into contact, the moving speed of the cam follower guided by the cam surface is changed, and the pattern of angular velocity and angular acceleration is changed. Allows arbitrary settings. In addition, by making the shape of this cam surface into a shape indicated by the polar coordinates according to the relational expressions 0 and 0 above, the temporal angular change of the swing axis becomes sinusoidal, thereby controlling the angular velocity and angular acceleration. is also sinusoidal.

[Example 1] An example of the present invention will be described below with reference to FIGS. 1 to 4.

1 and 2 show the main parts of this embodiment, and in the figures, reference numeral 1 indicates the oscillation generator of this embodiment.

This swing generating device 1 includes cam followers 3 provided on a swing shaft 2 at two positions spaced apart in the swing radial direction from the swing center and spaced apart in the swing direction, and these cam followers 3 sandwiched between the two cam followers 3. On both sides, a pair of rotary drive shafts 4 are provided along the surface-shaped swinging sleeve 2, and a cam surface is provided integrally with each of these rotary drive shafts 4 and is brought into movable contact with each of the cam followers 3. 5a, and a drive mechanism (not shown) for rotating these shafts in opposite directions is connected to each of the rotary drive shafts 4.

The cam surface 5a of each cam 5 has its rotation center 0.
1 as the origin, the center 0 of the cam follower 3 is shaped so as to form a movement locus represented by polar coordinates according to the following relational expressions (1) to (4).

n = ((Rax Sinθ)2+(La −Ra
X Cosθ) 1) I/l, ・, ■ψ−π−tan(A
/B)+α...■A=R
a-Sinθ・
・・■B=La-Ra-Co5θ
...■In the above formula, R; center of cam 5 0. Distance ψ from to the center O1 of the cam follower 3 brought into contact with the cam surface 5a; Angle Ra from a reference line orthogonal to the rotation axis of the cam; Distance La between the swing axis of the swing shaft and the rotation axis of the cam follower: Distance θ between the rocking axis of the rocking shaft and the rotating axis of the rotary drive shaft; Rocking angle α of the rocking shaft; Rotation angle of the cam; and if β1 is the maximum rocking angle, the rocking angle is 0.
is expressed by the following formula (■).

θ=β1・5in(nα)+β, ・
...■Here, n is the number of top portions formed on the cam 5, and in the illustrated example, since the top portions are formed at four locations, n=4.

In addition, β in the formula (■) is the center Ot of each cam follower 3.
& Center of swing axis 2 0. The included angle formed by the two straight lines obtained by connecting the lines is θ. Then, it is shown by the following formula 〇.

β, = (π-θ.)/2...
・■Furthermore, the center Oth swing axis 2 of the cam follower 3
The distance MRa from the center O5 of the swing axis 2 is the distance MRa from the center O5 of the swing axis 2. and the center of the rotational drive shaft 4 is 0. (the center of the cam 5).

and the center of and rotational drive ul of the cam follower 3.
The relationship between the distance RrNl and the center OI of 4 is set so as to satisfy the following equation (2).

Ra++1>La...■ The cam 5 of this embodiment formed under such conditions has a top part T where the cam surface 5a is farthest from the center 01, and a bottom part where the cam surface 5a is closest to the center 01. B is formed so that it exists in four places alternately in the direction of rotation, and
The top portion T and bottom portion B are formed in a continuous shape with a gentle curve.

Further, the front side of the top portion T in the rotational direction of the cam 14 is the first cam surface 5b, and the rear side of the top portion T in the rotational direction is the second cam surface 5c. As a result, the first cam surface 5b acts to press and move the cam follower 3, and the second cam surface 5c guides the return of the cam follower 3. Therefore, the cam follower 3 that is brought into sliding contact with the cam surface 5a is moved alternately on the first cam surface 5b and the second cam surface 5c as the cam 5 rotates (2), and
With respect to the rotary drive shaft 4, the cam 5 is stroked by the difference in height between the top portion T and the bottom portion B, so that the cam 5 can make four reciprocations per rotation.

Next, the operation of this embodiment will be explained.

First, when the circumferential rotary drive shaft 4 is rotated at a constant speed in opposite directions by the drive mechanism from the position shown in FIG. 1, one cam follower 3 (on the right side in FIG. is moved in the direction away from the rotational drive shaft 4 by the first cam surface 5b. This movement is done by Cam Follower 3.
This continues until the top portion T of the cam 5 is reached.

On the other hand, the other cam 5 (the cam 5 located on the left side in FIG.
), the other cam 5 is rotated in the opposite direction in synchronization with the one cam 5, so that the second cam surface 5c of the other cam 5 causes the cam follower 3 to be in contact with the other cam 5. is guided toward the rotational drive shaft 4 of. This movement continues until the cam follower 3 reaches the bottom portion B of the other cam 5.

By this operation, the swing shaft 2 is caused to swing from the maximum clockwise swing position to the maximum counterclockwise swing position in FIG. 1.

When both cams 5 continue to rotate further, the first cam surface 5b of the other cam 5 moves the other cam follower 3 in the direction away from the other rotational drive shaft 4, contrary to the above. and one cam follower 3
is guided by the second cam surface 5c of one of the cams 5 in a direction approaching one of the rotary drive shafts 4, thereby causing the swing shaft 2 to swing clockwise.

After that, the swing shaft 2 rotates at a rate of 4 reciprocations per rotation of both cams 5.
is shaken.

During such a rocking operation, the activity of the rocking shaft 2 is determined by the shape of the cam surface 5a of the cam 5, that is, the profile. The third
The swing pattern shown in the figure is obtained.

In other words, from the surface equation (■), the swing angle θ of the swing M2 is β1
・5in(nα)+β, and since α in the formula is a function of time, the temporal change in the swing angle θ is
The characteristic is as shown by curve A in FIG. 3.

From these facts, the temporal change in the swing of the swing shaft 2 can be obtained as a sine wave characteristic.

On the other hand, one cam 5 swings only in one direction, and at this time, the other cams 5 guide the cam follower 3 while being in contact with it, so that the swinging operation is easy. It will be done.

Here, the angular velocity ω generated at the swing axis 2 is the 0
It is obtained by differentiating the equation with respect to time t, and is expressed by the following equation (■).

ω=dθ/dt=n-a-N・β, Co5(n a )
-■ Then, when looking at the change in angular velocity ω using the rotation speed N of the cam 5 as a parameter, the curve n-
The characteristic is shown as D.

As is clear from these results, the angular velocity ω generated at the swing axis 2 similarly has sinusoidal characteristics.

Furthermore, the angular acceleration is obtained by differentiating the zero-based equation (2) with respect to time t, and is expressed by the following equation (2).

=dω/dt=-n"a-N"・β.・5in(n
a) -■ If we consider the change in this angular acceleration using the rotational speed N of the cam 5 as a parameter, as shown by curves E to J in Fig. 4, the angular acceleration generated at the swing shaft 2 also changes with the swing angle. Similar to θ and angular velocity ω, sinusoidal characteristics are given.

A large angular acceleration of I x 105 rad/sea" can be obtained at a relatively low rotation speed of the cam 5 of 1500 rpm.

Note that the shapes and dimensions of each structural member shown in the above embodiments are merely examples, and can be variously changed based on design requirements and the like.

For example, it is also possible to rotate both the cams 5 in the opposite direction to that of the above-described embodiment, and the number of top ITs of the cams 5 can be set to any number of six.

[Effects of the Invention] As explained above, according to the vibration generating device according to the present invention, the following excellent effects can be obtained.

As the swing characteristics of the swing axis, the temporal change in the swing angle, the angular velocity, and the angular acceleration can all be made into a sine wave, so that even when applied to a swing test machine, etc. The rocking conditions given to the non-test object can be treated as constant and known.

Therefore, the test results can be easily analyzed.

Further, by providing a sinusoidal swinging characteristic, forward and backward swinging movements can be performed symmetrically, which also facilitates the analysis of test results.

In addition, by using a pair of cams, only the pressing force is applied to the swing shaft, making it possible to obtain reliable swing motion and large angular acceleration. Since the cam follower can guide the return of the cam follower and reduce the backlash between them, a smooth rocking motion can be realized.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, and FIG. 1 is a front view showing the main parts, FIG. 2 is an enlarged view of the cam, and FIGS.
The figure is a characteristic curve diagram. 1... Oscillation generator, 3... Cam follower, 5... Cam, 5b... First cam surface,

Claims (1)

[Scope of Claims] Cam followers provided on the swing shaft at two positions spaced apart from the center of swing in the swing radial direction and spaced apart in the swing direction; A pair of rotary drive shafts provided along the rocking shaft, and a cam having a cam surface that is integrally provided with each of these rotary drive shafts and is movably brought into contact with each of the cam followers, and each of the cams The cam surface of the cam follower has its center of rotation as the origin, and the center of the cam follower is one of the following (1) to (4).
1. A vibration generating device characterized in that the vibration generating device is shaped to have a movement locus represented by polar coordinates according to the relational expression. R={((Ra×Sinθ)^2+(La−Ra×Co
sθ)^2＾1^/^2...(1) ψ=π-tan(A/B)+α...(2) A=Ra・Sinθ...(3) B=La-Ra・Cosθ...(4) However, R: Distance ψ from the center of the cam to the center of the cam follower that is brought into contact with the cam surface; Angle Ra from the reference line orthogonal to the rotational axis of the cam; Rotation of the swing axis Distance La between the axis and the rotation axis of the cam follower; Distance θ between the rotation axis of the swing shaft and the rotation axis of the rotary drive shaft; Swing angle α of the swing shaft; Rotation angle of the cam