JPH0656178B2 - Vibration control device for rotating body - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an improvement of a vibration damping device mainly used for a vertical rotary body.

[Technical background of the invention and its problems]

As a vibration control device for suppressing the vibration of the vertical rotary body,
Various types have been considered, but among them, there is one that utilizes the shear resistance of the liquid film as a damping force. This liquid film shearing type vibration damping device is designed to perform a damping action by a reaction force when the liquid film is forcibly sheared, and has a characteristic of excellent responsiveness.

By the way, among such conventional vibration damping devices for rotating bodies, a so-called "hanging type" is generally configured as shown in FIG.

That is, reference numeral 1 in the drawing is an oil tank in which the upper surface is opened and the lubricating oil P is accommodated inside, and the inner surface 2 of the bottom wall of this oil tank 1 is formed into a highly accurate flat surface so that it can also serve as the base. .
The inner diameter of the opening of the oil tank 1 is formed to be larger than that of the other portion, and the step portion 3 is formed at the connecting portion between the large diameter portion and the small diameter portion. An annular fixing plate 4 is provided on the step 3 of the oil tank 1.
Are fitted.

In the oil tank 1, a movable body 5 is arranged so as to face the inner surface 2 of the bottom wall of the oil tank 1. The movable body 5 is formed in a disc shape as a whole, and a thrust bearing 7 for supporting a lower shaft 6 of a vertical rotary body (not shown) is fixed to the central portion of the upper surface of the movable body 5. The movable body 5 is suspended and supported by the fixed plate 4 via a plurality of suspension bars 8 made of an elastic material and arranged in the circumferential direction. The suspension bar 8 has a function of holding a minute gap Q between the movable body 5 and the inner surface 2 of the bottom wall, and also elastically imparts a centripetal force to the movable body 5 at all times, so that when the movable body 5 vibrates. Has a function of moving the movable body 5 in a direction orthogonal to the axis.

The device configured as described above exhibits a vibration damping function as follows. That is, when the vertical rotating body tries to pass a critical speed or when a whirling force is generated in the vertical rotating body, the vibration of the lower shaft 6 increases, and as a result, the movable body 5 also vibrates in the horizontal direction. And In this case, since the oil film is formed in the minute gap Q, when the movable body 5 vibrates as described above, the oil film is sheared, and the vibration energy is absorbed by the energy consumption at the time of the shearing to suppress the vibration. I am trying to demonstrate.

By the way, in this main vibration damping device, the movable body 5 is
A structure in which the outer peripheral surface of the movable body 5 contacts the inner surface of the side wall of the oil tank 1 within the range of the maximum allowable amplitude so as not to vibrate beyond the maximum allowable amplitude of the movable body 5 determined by the maximum allowable strain of Has become. That is, the maximum allowable amplitude setting gap R is set between the outer peripheral surface of the movable body 5 and the inner surface of the side wall of the oil tank 1. However, when the gap R is formed between the outer peripheral surface of the movable body 5 and the inner surface of the side wall of the oil tank 1 as described above, the presence of the lubricating oil P in the gap R causes a so-called squeeze effect, and This causes a phenomenon that the rigidity with respect to the horizontal movement of 5 increases. When such a phenomenon occurs, smooth movement of the movable body 5 in the radial direction is hindered or an unstable vibration phenomenon is caused, resulting in deterioration of the vibration damping function, and the reliability as a vibration damping device. There was a risk of lacking in sex.

[Object of the Invention]

The present invention has been made in view of such circumstances, and an object of the present invention is to achieve the above-described squeeze without changing the maximum allowable amplitude setting gap formed between the movable body and the oil tank. An object of the present invention is to provide a highly reliable vibration damping device for a rotating body, which can suppress the influence of the effect and can always exhibit a sufficient damping function.

[Outline of Invention]

According to the present invention, the maximum allowable amplitude setting gap is defined on the outer peripheral portion of the movable body such that it projects in a flange shape in the direction toward the inner surface of the side wall of the oil tank or gradually becomes thinner as it approaches the inner surface of the side wall and the inner surface of the side wall. In addition, it is characterized in that an annular protrusion which suppresses the squeeze effect generated between the inner surface of the side wall and the inner surface of the side wall is set to a predetermined value or less.

That is, the damping constant D in this type of vibration damping device
Is a damping constant D _q in the small gap Q and a damping constant D _r in the maximum allowable amplitude setting gap R.
It is represented by the sum of and.

The damping constant D _q is generated by the viscous friction of the lubricating oil and represents the effect of the original damping action. D _q = η · S / δ _q (1) η; constant S; movable body and oil tank Area of the bottom wall facing the inner surface of δ _q ; represented by the width of the minute gap Q.

On the other hand, the damping constant D _r is generated by the squeeze effect, and D _r = η · (2l / δ _r ) ³ · πr / 2 (2) r; inner diameter of oil tank l; axial thickness of outer periphery of movable body δ _r : Calculated by the width of the maximum allowable amplitude setting gap R.

Usually, when designing a vibration damping device, since D _r is not taken into consideration, the design target value and the actual value will differ. For this reason, the above-mentioned unexpected unstable vibration may be caused.

Therefore, in this case, if the value of D _r / D _q is as small as possible, the influence of the squeeze effect can be eliminated.

Now, when D _r D _q is calculated from the above equations (1) and (2), D _r /
D _q = (2l / δ _r ) ³ · πrδ _q / 2S (3) Here, δ _q , r, S are parameters necessary for exhibiting a desired damping function, and δ _r is
It is a permissible value for preventing the destruction of the device. Therefore, in this case, D _r / D _q without affecting others.
In order to reduce the axial thickness l of the outer peripheral portion of the movable body.
Only the reduction should be made. The present invention has been made based on these points.

〔The invention's effect〕

According to the present invention, the damping action due to the squeeze effect can be suppressed, and inconveniences such as restraint of the movable body due to excessive damping and occurrence of unstable vibration do not occur. Therefore, a sufficient damping force can always be obtained, and a stable and highly reliable vibration damping action can be obtained.

Example of Invention

Embodiments of the present invention will be described below with reference to FIGS. 2 to 5. 2 to 5, the same parts as those in FIG. 1 are designated by the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

FIG. 2 is a diagram showing a vibration damping device according to the first embodiment of the present invention. This embodiment is different from the conventional example described above in the shape of the outer peripheral portion of the movable body 11.

That is, the movable body 11 according to the present embodiment is formed in a disk shape as a whole, and the brim portion 12 is projected to the lower end portion of the outer peripheral surface so that the area of the lower surface of the movable body 11 is larger than that of the peripheral upper surface. It has a different shape. The maximum allowable amplitude setting gap R described above is set between the outer peripheral surface of the brim portion 12 and the inner surface of the side wall of the oil tank 1.

Now, when the damping constant D _r at the maximum allowable amplitude setting gap R is suppressed to, for example, 1/10 or less of the damping constant D _q at the minute gap Q, from Equation (3), It is necessary to satisfy the condition of. Therefore, the brim 12
The axial thickness l of is set to a value that satisfies the above equation (4).

With such a configuration, the damping constant due to the squeeze effect can be suppressed to 1/10 or less as compared with the shear damping in the original minute gap Q, so that a good damping value close to the original set target value can be obtained. It can exert its function. Moreover, in this case, the maximum allowable amplitude setting gap R, which is the same as the conventional one, can be secured between the outer peripheral surface of the brim portion 12 and the inner peripheral surface of the side wall of the oil tank 1, so that it has another effect. Nor.

FIG. 3 is a diagram showing a vibration damping device according to a second embodiment of the present invention.

This embodiment is an example in which the present invention is applied to a vibration damping device using a thrust rolling bearing 22 for supporting a movable body 21.

That is, in FIG. 3, the oil tank 1 is formed into a highly precise flat surface such that the portion 23 located at the peripheral edge portion on the inner surface of the bottom wall serves as the base surface, and at the central portion on the inner surface of the bottom wall,
The recess 24 is formed. A convex portion 25 that enters the concave portion 24 is formed in the central portion of the lower surface of the movable body 21. Between the movable body 21 and the inner surface of the bottom of the recess 24, a thrust load applied to the movable body 21 is supported while a minute gap Q is provided between the movable body 21 and the portion 23, and the movable body 21 is supported. A thrust rolling bearing 22 is provided to support the shaft movably in a direction orthogonal to the axis. The rolling bearing 22 includes an annular first spacer 26 fixed to the lower surface of the movable body 21, an annular second spacer 27 fixed to the inner surface of the bottom wall of the recess 24, and the first and second spacers. It is composed of a plurality of spheres 28 interposed between 26 and 27, and a retainer 29 for always keeping the relative positional relationship of these spheres 28 in the circumferential direction constant. The retainer 29 is configured by providing an annular plate with a hole into which the spherical body 28 is fitted. The convex portion 25 and the concave portion 2
Between the inner surface of 4 and a means for automatically returning the movable body 21 to a fixed position, for example, a spring 30 is stretched.

A flange 31 is formed on the outer periphery of the movable body 21. A maximum allowable amplitude setting gap R is provided between the outer peripheral surface of the brim portion 31 and the inner surface of the side wall of the oil tank 1.

Even in such a vibration damping device using the thrust rolling bearing 22 , a good vibration damping function can be exhibited by applying the present invention.

The present invention is not limited to the above embodiment. For example, if it is possible to sufficiently secure the facing area S between the movable body and the inner surface of the bottom wall of the oil tank, the brim portion 34 may be formed on the upper end portion of the movable body 35 as shown in FIG. May be. Further, the outer circumference of the movable body does not need to be formed into a brim shape, and as shown in FIG.
The outer peripheral portion of the movable body 36 may be tapered.

As described above, the present invention can be variously modified and implemented without departing from the scope of the invention.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional suspension type vibration damping device for a rotating body utilizing shearing of a liquid film, and FIG. 2 shows a vibration damping device for a rotating body according to a first embodiment of the present invention. FIG. 3 is a vertical sectional view showing a vibration damping device for a rotary body according to a second embodiment of the present invention, and FIGS. 4 and 5 are rotary bodies according to other embodiments of the present invention. It is a longitudinal cross-sectional view showing only a main part of the vibration damping device for a vehicle. 1 ... Oil tank, 2 ... Bottom wall inner surface, 3 ... Step portion, 4 ... Fixing plate, 5,
11, 21, 35, 36 ... Movable body, 6 ... Lower shaft, 7 ... Thrust bearing, 8 ... Suspension rod, 12, 31, 34 ... Collar portion,
22 ... Thrust rolling bearing, 23 ... Base portion, 24 ... Recessed portion, 25 ... Convex portion, 26 ... First spacer,
27 ... second spacer, 28 ... sphere, 29 ... retainer,
30 ... Spring, P ... Lubricating oil, Q ... Micro gap, R ... Maximum allowable amplitude setting gap.

Claims (1)

[Claims] 1. A maximum permissible amplitude setting gap is provided between an oil tank containing lubricating oil, a horizontally extending base provided in the oil tank in a stationary state, and on the base and an inner surface of a side wall of the oil tank. A movable body which is disposed so as to be submerged in the lubricating oil through the lubricating oil and which supports a thrust bearing for supporting a vertical rotating body; and the movable body which is provided between the movable body and a stationary portion in the oil tank. A movable body supporting means for movably supporting the rotating body in a direction orthogonal to the axis of the rotating body and maintaining a minute gap between the movable body and the base, which can form an oil film extending only in the horizontal direction. In the vibration damping device for a rotating body, the outer wall of the movable body is formed into a flange shape in a direction toward the inner wall of the oil tank or gradually protrudes into a thin shape as the inner wall approaches the inner wall. In front of the inside Maximum permissible rotation-body vibration damping device, characterized in that the annular projection is provided to keep the squeeze effect less than a predetermined generated between the inner surface of the side wall as well as defining the amplitude setting gap.