JPS649065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration exciter capable of exerting an excitation force by rotating a mass body, and in particular to a vibration exciter that applies an excitation force to a test object such as a vehicle. The present invention relates to a vibrator suitable as a vibration simulator for early detection of chatter vibrations, etc.

As a conventional vibration exciter of this kind, there is one as shown in Fig. 1, in which a mass is attached to the outer end of an arm b having a length R that is fixed to a rotating shaft a and rotates integrally with the rotating shaft a.
A weight c of m ₁ is attached, and a large excitation force can be obtained by the centrifugal force F ₁ generated by rotating the weight c.

By the way, this centrifugal force _F1 , that is, the excitation force, increases in proportion to the square of its angular frequency ω, as shown by the broken line in Figure 5, if the mass and radius of rotation of the weight c are constant. In such a conventional vibrator, there is a problem that when the angular frequency ω is increased, the excitation force may become extremely large, which can be dangerous.

The present invention is an attempt to solve these problems, and aims to provide a centrifugal system in which the excitation force can be held down to a predetermined value even when the angular frequency ω is increased by controlling the centrifugal force. The purpose of this invention is to provide a force-controlled vibration exciter.

For this reason, the centrifugal force control type vibration exciter of the present invention has a first mass body disposed at a position apart from the rotation axis and rotates together with the rotation axis, and a first mass body disposed at a position apart from the rotation axis. and a second mass body movable with respect to the rotating shaft, the second mass body is configured to generate a second centrifugal force in a direction that reduces the first centrifugal force applied to the first mass body. The second mass is arranged so as to rotate together with the rotating shaft at a position subjected to centrifugal force, and the rotation radius of the second mass body is adjusted according to the rotational speed of the rotating shaft. In order to control the second centrifugal force applied to the body, the second mass body is connected to the rotation axis,
It is characterized by being supported so as to be elastically movable in the radial direction.

In the above-mentioned centrifugal force controlled vibration exciter of the present invention, when the rotating shaft is rotated by an appropriate means, the first mass body that rotates together with the rotating shaft has a first mass that is proportional to the square of the angular frequency. It acts to generate centrifugal force.

On the other hand, the second mass body is arranged so as to rotate together with the rotation shaft at a position where it receives a second centrifugal force in a direction that reduces the first centrifugal force applied to the first mass body. Since the rotating shaft is supported so as to be elastically movable in the radial direction, as the rotational speed of the rotating shaft increases, it moves outward in the radial direction, thereby reducing the first centrifugal force. Second
It acts to generate centrifugal force.

In this way, the overall excitation force is held down to a predetermined value.

Below, a centrifugal force-controlled vibrator as an embodiment of the present invention will be explained with reference to the drawings. Fig. 2 is a front view seen from the - arrow line in Fig. 3, and Fig. 3 is a cross-sectional view of its main parts. The side view shown in FIG. 4 is a schematic diagram for explaining the effect, and both FIGS. 5 and 6 are graphs for explaining the effect.

As shown in Figures 2 and 3, a rotating shaft 4 is disposed on the base 1 via bearings 2 and 3, and a thick circular plate 5 is fixedly attached to the rotating shaft 4. It is being

Further, the rotating shaft 4 is connected to an electric motor 7 via a gear mechanism 6 at the end of the shaft. Therefore, when the electric motor 7 is operated, the rotating shaft 4 rotates, and the disc 5 also rotates accordingly. I'm starting to do that.

By the way, a main weight 8 serving as a first mass body is fastened to a peripheral portion of the disc 5, that is, at a position spaced apart from the rotating shaft 4, using bolts and nuts.

Furthermore, as shown in FIG.
A recess 9 having a depth in the radial direction of the disk 5 is formed, and in this recess 9, an auxiliary weight 10 as a second mass body and a telescoping end are attached to the auxiliary weight 10. A spring 11 is loaded.

The fixed end of this spring 11 is attached to a presser plate 12 that closes the opening of the recess 9.

Therefore, when the rotating shaft 4 rotates, the main weight 8
The auxiliary weight 10 rotates together with the rotating shaft 4, and along with this rotation, the auxiliary weight 10 has a second centrifugal force in a direction that reduces the first centrifugal force applied to the main weight 8. It's starting to take a lot of force.

Furthermore, since this auxiliary weight 10 is supported by a spring 11 so as to be elastically movable in the radial direction with respect to the rotating shaft 4, as the second centrifugal force increases as the rotational speed increases, this The accompanying spring 11 contracts, and the rotation radius of the auxiliary weight 10 is adjusted to become larger.

Next, the excitation force F obtained by the vibrator of the present invention will be explained in detail using FIG. 4, which schematically shows the vibrator shown in FIGS. 2 and 3.

First, the first centrifugal force F 1 applied to the main weight 8 and the second centrifugal force F ₂ applied to the auxiliary weight 10 are expressed by the following equations (1) and (2) _, respectively.

F ₁ = m ₁ Rω ² …(1) F ₂ = m ₂ rω ² = Kx …(2) Here, m ₁ is the mass of the main weight 8, m ₂ is the mass of the auxiliary weight 10, and R is the main weight. The radius of rotation of the weight 8, r is the radius of rotation of the auxiliary weight 10 when the angular frequency is ω,
K represents the spring constant of the spring 11, and x represents the displacement of the spring 11.

Furthermore, if the distance from the center line of the rotating shaft 4 to the center of gravity of the auxiliary weight 10 when the rotational speed is 0 is r ₀ , then the displacement x is expressed by the following equation (3).

x=r−r ₀ …(3) Therefore, from equation (2), m ₂ rω ² =K(r−r ₀ )
Therefore, r=Kr ₀ /(K−m ₂ ω ² ) …(4) ∴F ₂ =m ₂ Kr ₀ ω ² /(K−m ₂ ω ² ) …(5) Now, F ₁ >F If we set each constant so that it becomes ₂ ,
The overall excitation force F is F=F ₁ −F ₂ =K(m ₁ R−m ₂ r ₀ )−m ₁ m ₂ Rω ² /K−m ₂ ω ²・
ω ² ...(6) If this F is plotted on a graph with ω as a variable, it will look like the curve shown by the solid line in Figure 5.

Therefore, according to the vibrator of the present invention, even if the angular frequency ω increases, the excitation force F does not increase indefinitely, but is kept below a predetermined value, so it is safe.

In addition, in the case of this embodiment, as shown in FIG. 3, the outer end of the spring 11 is fixed by the presser plate 12 to restrict the increase in the rotation radius of the auxiliary weight 10, so that the angular frequency Even if ω exceeds ω ₁ , a large negative centrifugal force will not occur.

Note that if the spring constant K of the spring 11 is made to have nonlinear characteristics as shown in FIG. 6, even if the angular frequency ω increases, the excitation force characteristics can be made flat to some extent.

By the way, in FIGS. 2 and 3, reference numeral 13 indicates a mounting leg for mounting this vibrator on the test object 14.

Since the centrifugal force controlled vibrator of the present invention is configured as described above, in order to apply an excitation force to the test object 14, first attach the present vibrator to the test object 14 via the legs 13. and fix it.

Next, when the electric motor 7 is operated to rotate the rotary shaft 4, disk 5, etc. at various rotational speeds, the excitation force F corresponding to each rotational speed, that is, each angular frequency ω, is This excitation force F causes the test object 14 to vibrate.

At that time, even if the rotation speed is increased, the fifth
As can be seen from the characteristic curve in the figure, since the excitation force F can be kept below a certain value, the test object 14 can be vibrated extremely safely.

By the way, as in the above-mentioned embodiment, the auxiliary weight 1
0 is elastically movably supported by a spring 11 provided on the outside thereof, as shown in FIG.
This auxiliary weight 10 may be elastically movably supported by a spring 11 provided inside the auxiliary weight 10, and in this case as well, substantially the same effects as in the above embodiment can be obtained.

Note that the vibrator shown in FIG. 7 is provided with a stopper 15 that restricts an increase in the radius of rotation of the auxiliary weight 10 as the rotational speed increases.
The centrifugal force F ₂ of the first centrifugal force F ₁ is never greater than the first centrifugal force F 1 .

In FIG. 7, the same reference numerals as in FIGS. 2 to 6 indicate substantially similar parts.

In addition, as shown in FIG. 8, the auxiliary weight is arranged so as to rotate together with the rotating shaft 4 at two positions where it is subjected to second and third centrifugal forces in a direction that reduces the first centrifugal force applied to the main weight 8. Weights 10', 10'' may be provided, and each auxiliary weight 10', 10'' may be supported so as to be elastically movable in the radial direction of the rotating shaft 4 via springs 11', 11''. good.

As detailed above, according to the centrifugal force controlled vibrator of the present invention, the second mass body generates a second centrifugal force in a direction that reduces the first centrifugal force applied to the first mass body. The second mass body is arranged to rotate together with the rotating shaft at a position where the second mass body receives In order to control the second centrifugal force, the second mass body is supported so as to be elastically movable in the radial direction with respect to the rotating shaft, so that even if the rotational speed increases, the overall This has the advantage that the excitation force can be suppressed to a predetermined value or less, and the test object can be vibrated extremely safely.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a conventional vibrator, Figs. 2 to 6 show a centrifugal force control type vibrator as an embodiment of the present invention, and Fig. 2 is a schematic diagram of a conventional vibrator. −
Fig. 3 is a front view as seen from the arrow line, Fig. 3 is a side view showing the main part in cross section, Fig. 4 is a schematic diagram for explaining its function, and Figs. 5 and 6 are both for explaining its function. FIGS. 7 and 8 are both schematic diagrams showing a centrifugal force-controlled vibration exciter as another embodiment of the present invention. 1... Base, 2, 3... Bearing, 4... Rotating shaft,
5...Disk, 6...Gear mechanism, 7...Electric motor, 8
...Main weight as the first mass body, 9...Recess,
10, 10', 10''...Auxiliary weight as a second mass body, 11, 11', 11''...Spring, 12...
Holding plate, 13... mounting leg, 14... test object,
15... Stoppa.

Claims (1)

[Claims] 1. A first mass body disposed at a position distant from the rotation axis and rotating integrally with the rotation axis, and a second mass body disposed at a position remote from the rotation axis and movable with respect to the rotation axis. In the vibration exciter, the second mass body rotates together with the rotating shaft at a position where the second mass body is subjected to a second centrifugal force in a direction that reduces the first centrifugal force applied to the first mass body. and in order to control the second centrifugal force applied to the second mass body by adjusting the radius of rotation of the second mass body according to the rotation speed of the rotation shaft, A centrifugal force controlled vibration exciter, wherein the second mass body is supported so as to be elastically movable in the radial direction of the rotation shaft.