JPS6230566A - Damping device for rotor - Google Patents

Abstract

PURPOSE:To develop high damping effect even during the rotation of a rotor at a high speed exceeding inherent vibration frequency, by absorbing unstable vibration by providing a vibration absorber consisting of a spring and mass to a movable body. CONSTITUTION:For example, three masses 13 and three springs 14 are provided to the part having no minute gap Q of a movable body 4. In this case, the masses 13 and the springs 4 are combined so that the wt. of each mass 13 and the spring rigidity of each spring 4 are selected so as to have inherent vibration coinciding with the inherent vibration frequency of the rotor to be preliminarily damped. Each mass 13 is formed into a ring shape and arranged so as to be sunk in lubricating oil P. By this method, because the unstable vibration of the rotor, especially, the unstable vibration thereof in an up-and- down direction is effectively absorbed by a vibration absorber consisting of the masses 13 and the springs 14, the vibration of the movable body 4 and the rotor in the axial direction is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in an allocation device mainly used for a rigid rotating body.

[Technical background of the invention and its problems]

Conventionally, vibration damping devices for suppressing the vibrations of rigid rotating bodies are
Various methods have been considered, including one that utilizes the shear resistance of the liquid film as a damping force. This liquid film shear type vibration damping device performs a damping action using the reaction force when the liquid film is forcibly sheared.
It is characterized by excellent responsiveness.

By the way, such a vibration damping device for a rotating body generally has a second
It is configured as shown in the figure. The oil tank 1 is an oil tank with an open top and containing lubricating oil P inside, and a portion 2 located at the periphery of the inner surface of the bottom wall of the oil tank 1 is made of a highly accurate flat surface so that it can also be used as a base. is formed. A recess 3 is formed in the center of the inner surface of the bottom wall of the oil tank 1.

A movable body 4 is disposed within the oil tank 1 so as to face the inner surface of the bottom wall of the oil tank 1. This movable body 4 is formed into a disk shape as a whole, and a convex portion 5 that enters into the recess 3 is formed at the center of its lower surface, and a lower portion of a shaping rotating body (not shown) is formed at the center of its upper surface. Thrust bearing 7 supporting shaft 6
is fixed. A small gap Q is provided between the movable body 4 and the bottom inner surface of the recess 3 to support the thrust load applied to the movable body 4. A thrust rolling bearing is provided to support the movable body 4 so as to be movable in a direction orthogonal to the axis. The above-mentioned rolling bearing includes a first annular spacer 9 fixed to the lower surface of the movable body 4, a second annular spacer 10 fixed to the bottom inner surface of the recess 3, and the first and second spacers. It is composed of a plurality of spheres 11 interposed between 9 and 10, and a retainer 12 that keeps the relative positional relationship of these spheres 110 in the circumferential direction always constant.

The retainer 12 is configured by providing an annular plate with a hole into which the sphere 11 is inserted, and is arranged so as to slide on the upper surface of the second spacer 10 as the sphere 11 rolls.

Additionally, a means (not shown) is provided between the movable body 4 and the oil tank 1 for automatically returning the movable body 4 to its home position.

The allocation device configured in this manner exhibits a vibration damping function in the following manner. That is, when the vertical rotation attempts to pass through a critical speed or when a turning force occurs in the shaping rotating body, the movement of the lower shaft 6 increases, and as a result, the movable body 4 also tends to vibrate in the horizontal direction. do. In this case, since an oil film is formed within the minute gap Q, when the movable body 4 vibrates as described above, the oil film is sheared, and during this shearing, energy is consumed to absorb vibration energy and perform a vibration damping function. I try to make the most of it. At this time, the means for automatically returning the movable body 4 prevents rotation of the movable body 4 and applies centripetal force to the movable body 4.

By the way, in the vibration damping device for a rotating body configured as described above, heat due to mechanical loss generated in the thrust bearing 7 of the rotating body is transmitted to the rIJlII oil P, resulting in an increase in the concentration of the lubricating oil P. Sometimes. However, since the viscosity of the lubricating oil P generally decreases as the temperature of the lubricating oil P increases, such a decrease in the viscosity of the lubricating oil P may significantly reduce the allocation function of the vibration damping device.

Therefore, in order to compensate for this decrease in the allocation function, an annular oil film is formed between the inner surface of the side wall of the oil tank 1 and the circumferential surface of the movable body 4 separately from the oil film, and this annular oil film provides a so-called squeezing effect. A device has been proposed. According to this device, in addition to the shear damping force, it is possible to obtain the damping force due to the squeeze effect. lI
It is possible to sufficiently compensate for a decrease in the allocation function due to a rise in the temperature of the clean oil P.

However, in a vibration damping device that also uses a squeeze effect, when the movable body 4 is photographed, the inner surface of the side wall of the oil tank 1 and the movable body 4 are
There is a problem in that cavitation occurs between the cylindrical surface and the circumferential surface of the cylindrical material, and the air bubbles generated at that time enter the minute gap Q and extremely reduce the shear damping force.

In any case, the damping ability will be significantly reduced due to the rise in the temperature of the lubricating oil P, so if the rotating body is rotating beyond its natural frequency, This may cause unstable vibrations that cause the rotating body to rotate, and this unstable vibration may cause damage to the rotating body.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to reduce the natural frequency caused by a decrease in damping ability even when the rotating body is rotating at high speed exceeding its natural frequency. It is an object of the present invention to provide a vibration damping device for a rotating body that can damp unstable vibrations that swing around at the same frequency as that of a rotating body.

[Summary of the invention]

The gist of the present invention is to use a vibration absorber consisting of a spring and a pawn shop,
The purpose of this vibration absorber is to absorb unstable imaging (particularly vibration in the axial direction) of the rotating body.

That is, the present invention provides an oil tank containing lubricating oil, a first horizontally extending base stationary within the oil tank, and a vertically extending second base stationary within the oil tank. and the first base submerged in the lubricating oil.
and a movable body that is disposed opposite to the second base via a minutely thick oil film and that supports a thrust bearing for supporting the chamber-shaped rotary body, and a movable body that is provided between this movable body and the oil tank. a vibration damping device for a rotary body, comprising a movable body supporting means that supports movable body supporting means movably in a direction orthogonal to an axial center line of the rigid rotary body, the vibration damping device for a rotary body having a vibration damping device for a rotary body that has a vibration frequency substantially equal to the natural frequency of the rotary body; A vibration absorber consisting of a spring and a mass system having a natural frequency of .

〔Effect of the invention〕

When the rotating body rotates at high speed, heat is generated in the thrust bearing, and as the temperature of the lubricating oil increases, the viscosity of the lubricating oil decreases, so the shear damping force that utilizes the viscosity of the lubricating oil decreases significantly. In such a situation, the problem is self-supporting vibration in which the rotating body rotates at the same frequency as its natural frequency.

This unstable vibration diverges when the damping force is reduced.

However, according to the present invention, the mass provided in the movable body absorbs vibration energy even in the absence of shear damping, and the mass itself vibrates, thereby
Since the imaging energy is dissipated, the vibration of the rotating body can be effectively suppressed. Incidentally, since the natural frequency of the rotating body can be determined by calculation or by an excitation test, it is easy to select the quality of the spring in the present invention.

Therefore, according to the present invention, II using shear damping
The I-vibration device is capable of exhibiting a high vibration damping effect even when the temperature of the lubricating oil increases or when rotating a rotating body that includes a strong excitation force.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a vertical sectional view showing a schematic configuration of a vibration damping device for a rotating body according to an embodiment of the present invention, and the same parts as in FIG. 2 are indicated by the same symbols.

The difference between this embodiment and the device shown in FIG. 2 described above is as follows.
This is because a spring 113 and a spring 14 are attached to a portion of the movable body 4 that does not have a minute gap Q (the upper surface in FIG. 1). Here, the weight W) of the mass 13 and the spring rigidity (K
) is the natural frequency (ω) of the rotating body to be anti-vibration in advance
The combination is selected to have a natural vibration matching . In other words, the following relationship is satisfied. However, 9 is the acceleration of gravity. Further, the ring 1113 is formed in a ring shape and is placed above the movable body 4 so as to be immersed in lubricating oil. The springs 14 connect the weight 13 and the movable body 4, and are provided at three locations, for example.

With such a configuration, unstable vibrations of the rotating body, especially uncompetitive vibrations in the vertical direction, are effectively absorbed by the vibration absorber made of the mass 13 and the spring 14 provided on the upper part of the movable body 4. . That is, the vibration of the mass 114 can damp the axial vibration of the movable body 4 and the rotating body. Therefore, the allocation function can be improved and the vibration damping device becomes more effective.

Note that the present invention is not limited to the embodiments described above. In the above embodiment, the direction of action of the spring is in the vertical direction, but if the natural vibration of the rotating body to be damped is horizontal photography, the direction of action of the spring is set to be horizontal. etc., should be attached according to the vibration mode of the rotating body. Further, the mass is not limited to a ring-shaped mass, and may be divided into a plurality of parts. In general, the number of springs is not limited to three, and can be changed as appropriate depending on the specifications.

In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a vibration damping device for a rotating body according to an embodiment of the present invention, and FIG. 2 is a schematic configuration of a conventional vibration damping device for a rotating body that uses shearing of a liquid film. Show t! 1 is a sectional view. DESCRIPTION OF SYMBOLS 1... Oil tank, 2... Portion that becomes a base (first base), 3... Concave part (second base), 4... Movable body, 5... Convex part, 6...・Lower shaft, 7... Thrust bearing, 8... Thrust rolling bearing, P... Lubricating oil,
Q...Minute gap, 13...Weight, 14...Spring. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (2)

[Claims] (1) An oil tank containing lubricating oil, a first base stationary in the oil tank and extending in the horizontal direction, and a second base stationary in the oil tank and extending in the vertical direction. , the first and second parts are submerged in the lubricating oil.
A movable body is disposed opposite to the base of the base of the rotary body through a minute oil film and supports a thrust bearing for supporting a rigid rotating body, and a movable body is provided between the movable body and the oil tank, and A vibration damping device for a rotating body, comprising a movable body supporting means that supports the rotary body so as to be movable in a direction orthogonal to the axial center line of the rotary body, wherein the movable body has a natural vibration that is approximately the same as the natural frequency of the rotary body. 1. A vibration damping device for a rotating body, characterized in that a vibration damping device is provided with a vibration absorber consisting of a number of springs and a mass system. (2) The vibration absorber has a mass connected to the upper part of the movable body via a spring, and the mass of the vibration absorber is submerged in the lubricating oil. The vibration damping device for a rotating body according to item 1.