JPS61189316A - Vibration proof device of bearing - Google Patents

Abstract

PURPOSE:To improve vibration damping action by elastically supporting a sleeve mounted on a bearing for a stator by O-ring, and interposing a viscous fluid in a space between a portion of the sleeve below the O-ring position and the stator. CONSTITUTION:A ball bearing 2 is fixed to a rotary shaft 1 by a nut 7, and a sleeve 3 is installed at the outside-diameter surface of the ball bearing 2. The outside cylindrical surface of the sleeve 3 is elastically supported by O-ring 4 mounted on a stator 5. The sleeve 3 is axially projected over the support position of the O-ring 4, and the projected portion is immersed in a viscous fluid 8 stored in the stator 5. Further, a narrow cylindrical space S is composed of the outside cylindrical surface of the sleeve 3 immersed in the viscous fluid 8 and the inside cylindrical surface of the stator 5 for forming a fluid film due to the hydrodynamic squeezing action.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a vibration isolator for a rotating shaping machine, and particularly to a vibration isolator for a bearing that is suitable for elastically supporting a bearing and effectively suppressing vibrations of a rotating body. Regarding a shaking device.

[Background of the invention]

The rotor of a vertical turbomolecular pump is conventionally supported by ball bearings, which are easier to handle. Also.

This rotor rotates at high speed in order to obtain a high vacuum, but to prevent and suppress vibration of this rotor, a rubber ring is attached to the outer periphery of the ball bearing, and the damping of the rubber ring is utilized. Jitsukai Showa 4
The O-ring method shown in Publication No. 8-75025 has a simple, convenient, and well-known structure, and when a cylindrical gap is formed between the outer ring of the ball bearing and the bearing case and oil is interposed, the oil is removed. More effective damping can be expected due to the squeeze action.

However, rubber does not have sufficient oil resistance, and when rotating at high speeds, the frictional heat of the ball bearings heats the O-ring to high temperatures, making it susceptible to thermal deterioration.

The damping effect of elastic force decreases relatively early. As the supporting rigidity and damping effect of the ball bearings disappears, the vibration characteristics of the rotating body naturally become unstable, and the dynamic loads acting on the ball bearings increase, leading to deterioration of the ball bearings. If the vibration of the rotating body becomes significant, a part of the rotating body may rub against the stationary body and be damaged.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration isolating device for a bearing that has an excellent damping effect in order to operate a rotating body while suppressing vibration characteristics that are stable over a long period of time.

[Summary of the invention]

The present invention is characterized in that a sleeve is attached to the outer diameter surface of the bearing, the outer diameter surface of the sleeve is elastically supported by an O-ring, and the lower end of the sleeve attached to the bearing is immersed in a viscous fluid from the O-ring position. Furthermore, a gap is formed between the stationary body and the sleeve at the portion where the sleeve is immersed in the viscous fluid, and a damping effect is provided by the hydrodynamic action of the viscous fluid during vibration.6 [Embodiment of the Invention] ] Hereinafter, one embodiment of the present invention will be described with reference to FIG. In FIG. 1, a ball bearing 2 is fitted onto a rotating shaft 1 and fixed with a nut 7, and a sleeve 3 is attached to the outer diameter surface of the ball bearing 2.

Here, 6 is a holding plate of the ball bearing 2, and the outer diameter surface of the sleeve 3 is elastically connected to and supported by the stationary body 5 by two O-rings 4 provided on the stationary body 5 constituting the axle box. ing. In addition, the sleeve 3 protrudes in the axial direction beyond the supporting position of the O-ring 4, and this portion serves as the viscous fluid 8 stored in the stationary body 5.
It is immersed in.

Furthermore, the outer diameter surface of the sleeve 3 immersed in the viscous fluid 8 and the inner diameter surface of the stationary body 5 form a narrow cylindrical gap S for forming a fluid film by a hydrodynamic squeezing action. Therefore, because of this configuration, the O-ring 4 is not wetted by the viscous fluid 8 and is in a dry state.

Now, when the rotating shaft l vibrates, the ball bearing 2 and the sleeve 3 are elastically supported by the O-ring 4, so the vibration is transmitted in the radial direction. However, the viscous fluid 8 in the gap S formed by the sleeve 3 and the stationary body 5 works hydrodynamically to absorb vibration energy through a squeezing action, so that the vibration of the rotating shaft 1 is suppressed. Further, the temperatures of the ball bearing 2 and the sleeve 3 rise due to frictional heat caused by the rotation of the ball bearing 2, but the heat is radiated from the sleeve 3 to the stationary body via the viscous fluid 8. Therefore, by protruding downward in the axial direction of the sleeve 3, this part not only serves the purpose of suppressing vibrations, but also has the effect of cooling the ball bearing by increasing the heat dissipation area. Moreover, suppressing the temperature rise of the sleeve 3 is advantageous in terms of heat resistance when rubber is used for the O-ring 4.

Furthermore, in the case of the present invention, when rubber is used as the O-ring 4, oil is usually used as the viscous fluid 8, so in terms of oil resistance, the O-ring 4 is not immersed in the viscous fluid 8, so it can be used for a long time. It is advantageous to consider this.

In FIG. 2, the difference from FIG. 1 is that a cylinder 9 is also attached to the inner diameter surface of the protrusion of the sleeve 3, forming one cylindrical gap S2.

Therefore, the holes are provided so that the viscous fluid 8 uniformly enters the inner and outer diameter surfaces of the sleeve 3 that absorb vibrations S1 and S2.

Further, in the case of this configuration, since the cylinder 9 is installed, the amount of viscous fluid 8 can be reduced.

When using expensive fluids, there is also an advantage in terms of cost6.Note that the gap required to form a fluid film due to such a squeezing action is less than a few inches, but
Narrow gaps (0.1 mm) that are affected by machining accuracy
(below) is not necessary.

In Fig. 3, the sleeve 3 is shaped like a cup, and there is a gap S between the bottom surface of the sleeve 3 and the stationary body 5 due to two parallel surfaces.
The vibration is mainly absorbed by the shear friction resistance of the viscous fluid interposed between the two parallel arms.

In FIG. 3, the damping effect utilizes the shear friction of the viscous fluid present in the gap S, so the narrower the gap S, the better, and it is often set to <0.111111+ or less. Therefore, the heat dissipation from the lower surface of the sleeve 3 is good, and the damping effect is less degraded than in FIGS. 1 and 2.

Although this embodiment shows an example in which a ball bearing is used as the bearing, a sliding bearing may also be used, and the feature of the present invention is that the elastic support part by the O-ring and the damping part by the viscous fluid are separated.

〔Effect of the invention〕

According to the present invention, even if rubber is used as the O-ring, there is extremely little change in bearing support rigidity over time. Therefore, the vibration of the rotating body can be stably suppressed over a long period of time.

[Brief explanation of drawings]

1, 2 and 3 are longitudinal sectional views of an embodiment according to the invention. 1... Rotating shaft, 2... Bearing, 3... Sleeve, 4
...0 ring, 5...stationary body, 8...viscous fluid.

Claims (1)

[Claims] 1. The outer diameter surface of the sleeve attached to the outer diameter surface of the bearing is elastically supported by an O-ring against a stationary body, and the sleeve below the position where the O-ring is supported is immersed in the viscous fluid. A vibration isolating device for a bearing, characterized in that a gap is formed between two planes between the stationary body and the sleeve at a portion of the sleeve immersed in the viscous fluid.