JPH07158635A - Active control type inclined pad bearing - Google Patents

Abstract

PURPOSE:To provide an inclined pad bearing able to obtain vibration damping performance and load resisting performance exceeding the limit of a conventional pad bearing. CONSTITUTION:In a journal oil bearing for a rotary machine, plural pads 4 are supported to a cylindrical bearing outer shell 2 respectively by one support 3, and the supports 3 are bent by piezoelectric elements fitted to one or plural supports 3 to control the inclination of the pads 4. The fluid force of an oil film is thereby changed actively so as to improve load force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active control type inclined pad bearing, and more particularly to a journal oil bearing for rotary machines (blowers, compressors, steam turbines, etc.) for plants and buildings, and particularly to prevent shaft vibration. The present invention relates to a bearing device that can be actively performed.

[0002]

2. Description of the Related Art FIG. 2 shows a sectional view of a conventional tilted pad bearing. The tilted pad bearing is a kind of journal oil bearing for a rotary machine, and a plurality of pads 4 are supported on a cylindrical bearing shell 2 by a column 3 respectively. Oil is filled between the shaft 1 and the bearing shell 2. The pad 4 and the pillar 3 are made of metal integrally formed with the outer shell 2,
When the shaft 1 rotates, the circumferential surface of the shaft 1 slides on the sliding surface 4a of the pad 4.
And slide. The portion of the pad 4 supported by the column 3 at the center does not deform, but the tip portion of the pad 4 elastically deforms due to the load force of the shaft 1. A wedge-shaped oil film is formed between the circumferential surface of the rotary shaft 1 and the sliding surface 4a of the pad, and high vibration damping performance and load bearing performance can be obtained by the fluid force of the wedge-shaped oil film. . In this way, the tilted pad bearing can realize more stable shaft support than the conventional normal journal oil bearing due to the elastic deformation of the pad tip portion and the formation of the wedge-shaped oil film.

[0003]

However, even with such a conventional pad bearing, there are cases where the preset load capacity is exceeded due to changes in operating conditions or due to changes in the load conditions of the rotating machine. In this case, since the damping function of the wedge-shaped oil film in the gap between the pad and the shaft is not exerted by the fluid force, the conventional pad bearing has a certain limit.

The present invention has been made in view of the above-mentioned conventional circumstances, and provides a tilted pad bearing capable of obtaining vibration damping performance and load bearing performance that exceed the limits of the conventional pad bearing. The purpose is to

[0005]

An active control type tilt pad bearing of the present invention is a journal oil bearing for a rotary machine, and a plurality of pads are supported by a cylindrical bearing shell by one column. The piezoelectric element attached to one or a plurality of columns of the columns bends the columns to control the inclination angle of the pad.

Further, a displacement sensor is attached to a support of the pad, and a compensation circuit and a power amplifier for outputting a current for controlling the inclination angle of the pad to the piezoelectric element based on an output signal of the displacement sensor are provided. It is characterized by

[0007]

The electrostriction phenomenon of the piezoelectric element attached to the support pillar that supports the pad allows the support pillar to bend and the tilt angle of the pad to be controlled. When the pad tilt angle changes,
The thickness of the wedge-shaped oil film in the gap between the sliding surface of the pad and the shaft changes, and the fluid force of the oil film can be actively changed to improve the load capacity of the bearing.

In the active control of the tilt angle of the tilted pad, the displacement sensor attached to the pad support detects the tilt of the pad, and the phase and gain of the detected signal are adjusted by the compensation circuit to prevent the vibration. By supplying a current from the power amplifier to the piezoelectric element so as to provide a damping force and performing dynamic control, it is possible to add an active vibration damping function and improve the load capacity. That is, it is also possible to forcibly generate the damping force and suppress the vibration by dynamically controlling according to the whirling frequency of the shaft.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view of an active control type inclined pad bearing according to an embodiment of the present invention. The structure in which the rotary shaft 1 is supported by a plurality of pads 4 and the space between the rotary shaft 1 and the cylindrical bearing shell 2 is filled with oil is similar to that of the conventional tilted pad bearing described above, The same components are designated by the same reference numerals, and duplicate description will be omitted.

In the inclined pad bearing of this embodiment, the stay 7
The piezoelectric element 5 is provided between the column 3 and the column 3. The piezoelectric element 5 fixed to the stay 7 is
A minute strain proportional to the current is generated to bend the support column 3 and change the inclination angle of the sliding surface 4a of the pad 4. In this embodiment, the bearing outer shell 2, the support column 3, the pad 4, and the stay 7 are all formed by integral processing of metal. It should be noted that the members constituting these bearings may be manufactured individually and assembled into the shape shown in FIG. 1 instead of being integrally processed.

Therefore, a control current is applied to the piezoelectric element 5 to apply a strain force to the support column 3 to tilt the sliding surface 4a of the pad 4. Due to the inclination of the sliding surface 4a of the pad 4, the shape of the wedge-shaped oil film between the rotary shaft 1 and the sliding surface 4a changes,
The fluid force changes. Therefore, by changing the fluid force of the oil film according to the load condition, the vibration of the rotary shaft 1 can be suppressed and the load capacity of the bearing can be improved.

Similarly, a displacement sensor 6 is provided between the column 3 and the stay 7. The displacement sensor 6 is a strain gauge capable of taking out an electrical output, and its output is amplified by the sensor amplifier 10. Then, the output of the sensor amplifier 10 is input to the compensation circuit 11, and the phase and amplitude are changed by the compensation circuit 11 so that the tilt angle is changed according to the whirling frequency of the shaft and the damping force is forcibly generated. Adjusted. The dynamic control signal output from the compensation circuit 11 is power-amplified by the power amplifier 12, and a control current is applied to the piezoelectric element 5. Strain is generated in the piezoelectric element 5 according to the applied control current, and a bending force is applied to the support column 3 to tilt the sliding surface 4a of the pad 4.

As described above, the compensating circuit 11 dynamically controls the tilt angle in accordance with the whirling vibration frequency of the shaft to forcibly apply the damping force to the whirling vibration of the rotary shaft 1. It is also possible.

In the embodiment shown in FIG. 1, the piezoelectric element 5 is illustrated so as to control only one column 3. However, the other columns are similarly provided with piezoelectric elements, and the same structure is used. You may perform various controls. As described above, various modifications can be made without departing from the spirit of the present invention.

[0015]

As described above, according to the active control type inclined pad bearing of the present invention, the inclination of the sliding surface of the inclined pad is actively controlled by the piezoelectric element, so that the inclination of the conventional inclined pad bearing is It is possible to control beyond the limit, improve the load capacity of the bearing, and improve the safety of the rotating machine.

[Brief description of drawings]

FIG. 1 is a sectional view of an active control type inclined pad bearing according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional active control type inclined pad bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 2 bearing outer shell 3 support 4 pad 5 piezoelectric element 6 displacement sensor 7 stay 10 sensor amplifier 11 compensation circuit 12 power amplifier

Claims (2)

[Claims] 1. A journal oil bearing for a rotary machine, wherein a plurality of pads are supported on a cylindrical bearing shell by a column, respectively, and are attached to one or a plurality of the columns. An active-controlled tilted pad bearing, wherein the pillar is bent by a piezoelectric element to control the tilt angle of the pad. 2. A displacement sensor is attached to a support of the pad, and a compensation circuit and a power amplifier are provided for outputting a current for controlling the tilt angle of the pad to the piezoelectric element based on an output signal of the displacement sensor. The active control type tilt pad bearing according to claim 1, wherein