JP2659829B2 - Bearings for vibration suppression - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping bearing applied to a sliding bearing, and more particularly to a shaft for a compressor, a supercharger, a steam turbine, a gas turbine or a pump. The present invention relates to a vibration damping bearing suitable for supporting a rotating body operated at a high rotation speed.

2. Description of the Related Art Generally, a bearing supports the weight of a rotating body for stable rotation of the rotating body, and also needs to absorb a forced vibration force due to a shape imbalance of the rotating body. Is required to suppress the self-excited whirling due to the action of the fluid in. For this purpose, it is necessary that a sufficient damping action occurs in the rotating shaft system including the bearing. It has been found that the bearing portion is more effective at the place where the damping action occurs than the rotating body itself. As a type in which a damping action occurs in the bearing portion, there is a slide bearing in which a rotating body is supported via a fluid. As a plain bearing having such a configuration, the second
2. Description of the Related Art A tilting pad bearing as shown in the drawings is conventionally known.

In the conventional configuration shown in FIG. 2, the upper bearing housing 1 and the lower bearing housing 2 are connected by a fastening bolt 3 to form a bearing housing 4. A plurality of circumferentially divided bearing pads 5, 6, 7, and 8 are accommodated in the bearing housing 4, and are each prevented from rotating and positioned. A rotating body 9 is rotatably supported inside the bearing pads 5, 6, 7, 8 on the axial center side.

In such a configuration, the static load and the fluctuating load generated by the operation of the rotating body 9 are transmitted to the bearing pads 5, 6, 7, 8 via the fluid 10 filled in the bearing housing 4. Under the load, the bearing pads 5, 6, 7, and 8 tilt and move with respect to the pivot 11, and as a result, the vibration damping action occurs in the bearing portion.

However, in such a conventional plain bearing, it is known that when the rotating body exceeds a certain number of rotations, the rotating body self-excitates due to the action of the fluid film (hereinafter, this phenomenon is referred to as oil whip). ).

Referring to FIG. 3, the mechanism of generating the oil whip will be described. When the center of the bearing is O _B and the center of the journal of the rotating body is O _J , the eccentric direction of the journal ( _{J B}
Component F _theta of fluid film force in the rotational direction at a right angle to the fluid film force component F _epsilon and this F _epsilon direction), each of the following (1),
It is known that it can be expressed by equation (2).

F _ε = μ (R / C) ² RL [(ω-2) F _ε ⁽¹⁾ + F _ε
⁽²⁾ ] (1) _Fθ = μ (R / C) ² RL [(ω−2) _Fθ ⁽¹⁾ + _Fθ
^{(2)] ...... (2)} μ: viscosity of the fluid, R: bearing radius, L: bearing width, C: bearing radial gap, omega: rotational angular velocity, epsilon: eccentricity = O _B O _J / C ,: eccentric Rate of increase rate, θ: Eccentric angle of journal,: Eccentric angle increase rate Here, F _ε ⁽¹⁾ , F _ε ⁽²⁾ , F _θ ⁽¹⁾ , and F _θ ⁽²⁾ are journal eccentricities of the rotating body. It is a function of ε and depends on the shape of the bearing. Equations (1) and (2) include the so-called coupled terms and include the term (ω-2), which are characteristics of the fluid film force of the bearing. (Ω
The term -2) indicates that the fluid in the fluid film is dragged by the journal of the rotating body and tends to flow on average at half the peripheral speed of the journal. Also, when the center of the journal of the rotating body oscillates around the center of the bearing, it can be seen that the fluid film force increases as ω increases more than 2.

The F _ε component of the fluid film force in the eccentric direction of the journal of such a rotating body is generally called a squeeze film pressure and is a force acting to reduce the eccentricity of the journal. It is preferable to increase the value. On the other hand, the _Fθ component of the fluid film force in the direction of rotation perpendicular to the _Fε component is generally called wedge film pressure, which is a force that promotes oil whip, and is not preferable for stable rotation of the rotating body. Things. Then, in the conventional tilting pad bearing shown in FIG. 2, although the F _ε component is generated by the above configuration, it has been devised to suppress the F _θ component.

However, even in the conventional tilting pad bearing shown in FIG. 2, the rotational speed of the rotating body 9 increases, and the mass of the bearing pads 5, 6, 7, 8 with respect to the pivot 11 increases. In the region of a high rotational frequency exceeding the natural frequency related to the above, it was impossible to suppress the _Fθ component of the fluid film force shown in FIG. 3, and there was a problem that an oil whip occurred.

The present invention has been made in order to solve such problems of the prior art, and even in a high rotation speed region where oil whip may occur in the rotating shaft system,
An object of the present invention is to provide a vibration damping bearing capable of suppressing the _Fθ component of the fluid film force and simultaneously increasing the _Fε component as shown in FIG.

Means for Solving the Problems In order to achieve the above object, the present invention provides a bearing housing, and a plurality of circumferentially divided bearings provided in the bearing housing and rotatably supporting a rotating body. In a vibration damping bearing including a pad, the plurality of bearing pads are housed with a gap in the bearing housing,
One end in the circumferential direction is fixed so as to be displaceable in the radial direction, and the other end in the circumferential direction is supported by a vibration device that vibrates in the radial direction.

According to such means, the bearing pad is vibrated in the radial direction by the vibrating device to generate a fluctuating pressure in the fluid film between the journal of the rotating body and the bearing pad based on the relative vibration between the two. This effectively generates a component of the fluid film in the eccentric direction of the journal of the rotating body (the F _ε component in FIG. 3), and a component of the fluid film force in the rotation direction perpendicular to the F _ε component. ( _Fθ component in FIG. 3) can be suppressed to suppress oil whip, and the load capacity and damping performance of the bearing are almost proportional to the amplitude and frequency of the bearing pad to be excited. Can be increased.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, an upper bearing housing 20 and a lower bearing housing 21 are connected by a fastening bolt 22,
A bearing housing 23 is formed. Inside the bearing housing 23, a plurality of circumferentially divided bearing pads 24, 25,
26 are accommodated with a gap 44, and are each stopped and positioned. These bearing pads 24, 25,
One end in the circumferential direction of 26 is a positioning jig 27, 28,
By means of 29, it is attached to the bearing housing 23, and enables minute displacement in the radial direction. A rotating body 30 is rotatably supported inside the shaft pads of the bearing pads 24, 25, and 26.

The other ends of the bearing pads 24, 25, and 26 in the circumferential direction are respectively provided on the outer surfaces of the shaft centers through the excitation force amplifying devices 31, 32, and 33, and the laminated piezoelectric type outside the bearing housing 23. Vibration devices 34, 35, 36
It is configured to be supported by. Exciting force amplifying device 31, 32,
33 and the vibration devices 34, 35, 36
It is fixed to the bearing housing 23 by 7, 38, 39.
The fluid 40 is supplied to the inside of the bearing housing 23 from supply ports 41, 42, 43 provided in the bearing housing 23, and is supplied to the bearing pads 24, 2
The gap 44 between the rotating body 30 and the rotating body 30 is filled. The laminated piezoelectric vibrators 34, 35, and 36 can vibrate at a high frequency. By vibrating the bearing pads 24, 25, and 26 in the radial direction with these vibrators, the journal of the rotating body 30 and the bearing Pads 24, 25,
A fluctuation pressure is generated in the fluid 40 between the fluid 26 and the fluid 40 based on the relative vibration between them.

As a result, a component (F _ε component in FIG. 3) in the eccentric direction of the journal of the rotating body 30 is effectively generated, and
A component of the fluid film force in the rotational direction perpendicular to the F _ε component (third component)
(F _θ component in the figure) can be suppressed to suppress oil whip, and increase the load capacity and damping performance of the bearing almost in proportion to the amplitude and frequency of the bearing pad to be vibrated. be able to.

These effects are to maintain steady vibration of the bearing pad of 1/2 or more of the number of revolutions of the rotating body (relatively, it is equivalent to whirling of the journal of the rotating body). Therefore, it is preferable to set the vibration speed of the vibration device to a vibration frequency equal to or more than 1/2 of the rotation speed of the rotating body.

In the embodiment shown in FIG. 1, the vibration devices 34, 35, 36
Is a laminated piezoelectric vibration device, but the present invention is not limited to this, and another hydraulic or electromagnetic vibration device or the like may be applied. In the above embodiment, the number of the bearing pads is three. However, the present invention is not limited to this, and the number, size, arrangement, and mounting position of the vibrating device may be changed as desired. It can be selected accordingly.

As described above, according to the present invention, a bearing housing and a plurality of circumferentially divided bearing pads provided in the bearing housing to rotatably support a rotating body are provided. In the vibration damping bearing, the plurality of bearing pads are accommodated in the bearing housing with a gap therebetween, and one end in the circumferential direction is fixed so as to be displaceable in the radial direction. The end side is supported by a vibration device that vibrates in the radial direction, and the bearing pad is vibrated in the radial direction by this vibration device, so that the fluid film between the journal of the rotating body and the bearing pad is formed. Fluctuating pressure based on the relative vibration of the rotating body, thereby effectively generating a component of the fluid film in the eccentric direction of the journal of the rotating body (F _ε component in FIG. 3), and at right angles to the F _ε component. How to rotate The generation of the component of the fluid film force in the opposite direction (the _Fθ component in FIG. 3) can be suppressed, and the oil whip can be suppressed.
Further, the load capacity and the damping performance of the bearing can be increased almost in proportion to the amplitude and the frequency of the bearing pad to be vibrated, and therefore, the speed of the rotating body can be easily increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a vibration-damping bearing (slide bearing) according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a conventional vibration-damping bearing, and FIG. FIG. 23 …… Bearing housing, 24,25,26 …… Bearing pad, 30…
... Rotating body, 34,35,36 ... Exciting device.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Iwao Matsumoto 1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory (56) References JP-A-63-303214 (JP, A) Showa 64-11423 (JP, U) Actually open Showa 64-11424 (JP, U)

Claims (2)

(57) [Claims] An anti-vibration bearing comprising: a bearing housing; and a plurality of circumferentially divided bearing pads provided in the bearing housing and rotatably supporting a rotating body. A bearing pad is accommodated in the bearing housing with a gap, and one end in the circumferential direction is fixed so as to be displaceable in the radial direction, and the other end in the circumferential direction is vibrated in the radial direction. A vibration damping bearing characterized by being supported by a vibration device. 2. The vibration damping bearing according to claim 1, wherein the vibration speed of the vibration device is set to a vibration frequency which is equal to or more than 1/2 of the rotation speed of the rotating body.