JPS628648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating body shock absorbing device that facilitates vibration damping of a rotating body rotating at high speed, and particularly relates to a vibration damping device for a vertical rotating body whose upper part is supported by a bearing of extremely low rigidity such as a magnetic bearing. This invention relates to improvements to lower shock absorbers.

In the case of a vertical high-speed rotating body, a downward thrust force of several kilograms to several tens of kilograms may act on the lower bearing due to the weight of the rotating body.

Furthermore, when a rotating body is rotated at high speed, whirl force caused by the bearings and whirling force caused by air flow between the rotating body and the stationary part act, causing unstable whirling vibrations in the rotating body. There is. For this reason, appropriate shock absorbers are generally provided in the upper and lower bearings, but if the upper bearing has low rigidity and the lower bearing has high rigidity (centripetal spring constant), the whirling vibration mode will be such that only the upper part vibrates greatly.
The damping effect of the shock absorber installed in the lower bearing could not be expected, and unstable whirling vibrations sometimes occurred. Therefore, the stiffness of the lower bearing (centripetal spring constant)
is the same as or several times that of the upper part, for example, several kg/
cm to several tens of kg/cm is desirable.

In other words, as a lower shock absorber for such a vertical high-speed rotating body, it is possible to support downward thrust force of several kilograms to several tens of kilograms, and use a centripetal spring constant of several kilograms/cm to several tens of kilograms/cm to move the bearing in the angular direction of the rotating shaft. The problem is to provide a mechanism that provides soft support for the vibrations and has an appropriate damping effect for damping vibrations.

Conventional examples of rotating body shock absorbers for this purpose include:
There is one shown in Figure 3.

FIG. 3 shows a rotating shaft 22 connected to a rotating body 21.
By supporting the flanged cylindrical vibration transmitting body 24 with the ball bearing 26, which vibrates integrally with the pivot bearing 23 that supports the vibration transmitting body 24, the downward thrust force can be supported, and at the same time, the vibration transmitting body 24 can freely move in the direction perpendicular to the rotation axis. It enables movement, and also provides lubricating oil 2.
8 and the vibration transmitting body 2
The squeezing effect of the lubricating oil by the cylindrical gap 27 provided between the cylindrical gap 27 and the cylindrical gap 27 provides a vibration damping effect. The damper, which uses the squeezing effect of this cylindrical oil film, causes cavitation when the rotating body passes through a critical speed and vibrations increase due to unbalance.
There was a problem that a sufficient and stable damping effect could not be obtained. Furthermore, due to long-term use, the wear of the ball contact portion of the ball bearing 26 may impede the free movement of the vibration transmitter 24 in the direction perpendicular to the rotation axis, which may cause unstable vibrations such as whirl. be.

Therefore, the structure is simple, and the workability and assemblability are good.
There has been a demand for a rotating body shock absorber with excellent damping characteristics.

The present invention has been made in view of the above points, and the present invention is a vibration damping device for the lower shaft of a rotating body, which supports the downward thrust force from the rotating body and regulates the vibration in the radial direction of the lower shaft. To provide a rotating body shock absorber having a regulating damper, which has a simple structure, is easy to process and assemble, has excellent damping characteristics, and is free from concerns about longevity due to wear, etc. The purpose is to

That is, the present invention includes a rotating shaft connected to the lower part of a rotating body, a bearing that supports this rotating shaft, and three or more wire-like supports that support the thrust force acting on the bearing and provide centripetal action. and a damping generating movable plate that is fitted with a small gap around the outer periphery of a movable disc that is integrated with the bearing and placed on the bottom of an oil tank that accommodates the bearing. This is a rotating body shock absorber.

Hereinafter, one embodiment of a shock absorber according to the present invention will be described with reference to FIG.

In the figure, reference numeral 1 denotes an oil tank that stores lubricating oil 2 therein.A step b is provided at the upper end opening a of the oil tank 1, and an annular plate 3 is placed on this step b. The inner periphery of the annular plate 3 is provided with female threads at three or more locations on the circumference. The rotating shaft 8 is provided with a rotating body (not shown) at the upper part thereof, and is supported by a bearing 7 at the lower end of the shaft 8, and the bearing 7 is fitted into the support disk 6. Three or more circular recesses c are bored on the outer periphery of the lower surface of the support disk 6, and a disk integrally provided at the lower end of the wire-like support member 4 is provided in the recesses c at three or more locations on the circumference. The part d is fitted into the male thread b provided at the upper end of the wire-like support member 4 and the threaded sleeve 5.
By fixing these to the female threads e of the annular plate 3, the support disk 6 becomes suspended by three or more wire-like support members 4. Note that a screwdriver groove (not shown) is provided on the upper surface of the screw sleeve 5, and the wire-like support member 4 is connected to the annular plate 3.
The wire-like support member 4 acts as a double screw structure to prevent it from twisting when fixed to the wire. An annular flat plate 9 having a minute gap 10 is fitted into the outer periphery of the support disk 6 and placed on the bottom surface of the oil tank 1.

Thus, the wire-like support member 4 can not only support the downward thrust force applied from the rotating shaft 8, but also apply a centripetal force to the bearing 7 and support the rotational torque from the rotating shaft. When the rotating body passes a critical speed or whirls around, the support disk 6 transmits vibration to the annular flat plate 9 due to the squeezing effect of the minute gap 10 on its outer periphery, but the annular flat plate 9 vibrates in a horizontal plane. At this time, a damping force is generated due to the shear of the oil film in the minute oil film 11 formed between the oil tank 1 and the bottom surface of the oil tank 1, and vibration energy is absorbed.

Furthermore, when the annular flat plate 9 vibrates, a squeeze oil film is dynamically formed on its lower surface, causing the annular flat plate 9 to float, and as a result, an oil film 11 with an appropriate thickness is formed, and a stable damping effect is expected. .

FIG. 2 shows another embodiment of the present invention,
Another annular plate 1 is placed on top of the annular plate 9 in FIG.
2 is placed on it. A small radial gap 13 is provided between the annular flat plate 12 and the inner surface of the oil tank 1 on its outer periphery.

In this embodiment, the bearing vibrates and the annular flat plate 9
When the annular flat plate 9 vibrates, the annular flat plate 12 cannot move in the radial direction due to the squeezing effect of the oil film 13.
As a result of the relative movement, a minute oil film 14 is also formed on the upper surface of the annular flat plate 9, and a damping effect is added due to the shearing action of this oil film.

When whirling force acts on a rotating body, in order to rotate stably without generating whirl, it is necessary to reduce the centripetal force of the bearing and use what is called a soft support.
In the present invention, this can be achieved by increasing the length of the wire-like support member 4 and decreasing the diameter of the wire portion.

As explained above, according to the present invention, the means for forming an oil film is easy, and a large damping force can be generated, and the machining and assembly operations are very easy, and the bearing is supported flexibly to prevent whirling. Therefore, it is possible to provide a rotating body shock absorber that is stable against such unstable vibrations.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views showing respective embodiments of the shock absorbing device according to the present invention, and FIG. 3 is a longitudinal sectional view showing a conventional example. 1... Oil tank, 2... Lubricating oil, 3... Annular plate, 4
... Wire-shaped support member, 5 ... Threaded sleeve, 6 ...
...Support disk, 7... Bearing, 8... Rotating shaft, 9...
Annular flat plate, 10...Minute gap, 11...Oil film (shear section), 12...Annular flat plate, 13...Minute gap, 14...Oil film (shear section).

Claims (1)

[Claims] 1. A rotating shaft connected to the lower part of the rotating body, a bearing that supports this rotating shaft, and three or more wire-like support members that support the thrust force acting on this bearing and provide centripetal action; A rotary body buffer comprising: a movable plate for damping generation, which is fitted onto the outer periphery of a movable disc integral with the bearing with a minute gap and placed on the bottom surface of an oil tank housing the bearing. Device.