JPS61184217A - Rotary machine with movable thrust bearing - Google Patents

Abstract

PURPOSE:To enable the optional adustment of bearing gap by forming the bearing surface and the outer circumferential surface of a turning shaft to a tapered surface respectively, and making the thrust pad to be contacted with the thrust collar part of a body of rotation freely movable. CONSTITUTION:The sleeve bearing surface 9a of a bearing body 9 and the outer circumferential surface 4a of a companion pinion shaft 4 to be supported are formed in a tapered surface respectively. A movable thrust bearing 10 is of a thrust pad method, in which a piston 13 for hydraulic drive is provided to a thrust pad 11 and the thrust receiving surface can be optionally adjusted by hydraulic pressure. When speed transists critical speed at the time of starting, large amplitude is caused, and at this time the piston 13 is moved slidably toward right by supplying pressurized oil to a hydraulic chamber 16b through an oil pressure piping 18, and escaping the oil in a hydraulic chamber 16a to an oil pressure piping 17. Accordingly, the thrust pad 11 moves in the axial direction toward right by DELTAL from the dashed line to the solid line by pressing the thrust collar part 4b of the pinion shaft 4.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a rotating machine equipped with a movable thrust bearing,
In particular, the present invention relates to a rotating machine equipped with a movable thrust bearing, which is suitable for adjusting the vibration characteristics of devices such as blowers and compressors that are operated above high-order critical speeds.

[Background of the invention]

In general, in rotating machines such as blowers and compressors that are operated above a high-order critical speed, when the critical speed is exceeded at startup, there is a possibility that the impeller and casing may come into contact with each other due to large transient vibrations. be. In particular, in high-speed rotating machines with overhung impellers, this effect is significant, so it is necessary to keep the transient amplitude small, and a means to change the bearing characteristics is desired.

One way to change the characteristics of a bearing is to change the preload of the bearing pad with the aim of changing the spring constant of the bearing. For example, JP-A-57-”29811
There is a ``preload reduction device for tailing pad type bearings'' described in the publication, but this can be applied to tailing pad type journal bearings, but cannot be applied to sleeve type bearings.

Furthermore, the "damping bearing" described in JP-A-57-1822 has an outer circumferential surface of the bearing formed into a tapered surface, and a bearing support body having a tapered surface opposite to the tapered surface is placed between the bearing and the housing. The membrane gap of the fluid film damper between the tapered surfaces is made variable by moving the bearing support body in the axial direction. This adjusts the gap on the back side of the bearing, but no consideration was given to adjusting the bearing gap itself.

[Purpose of the invention]

The present invention was made in view of the problems of the prior art described above, and allows the bearing characteristics to be changed by arbitrarily adjusting the bearing gear pitch. In particular, in high-speed rotating machines, the bearing gap is increased at startup, The object of the present invention is to provide a rotating machine equipped with a movable thrust bearing that can prevent contact between an impeller and a casing by reducing the transient vibration value when exceeding a critical speed.

[Summary of the invention]

The configuration of a rotating machine equipped with a movable thrust bearing according to the present invention is such that the sleeve bearing surface of the bearing body that supports the rotating body and the outer peripheral surface of the supported rotating shaft are each formed into a tapered surface, and the bearing body A movable thrust bearing is provided on a side surface of the rotating body, the movable thrust bearing consisting of a thrust pad to be brought into contact with the thrust collar portion of the rotating body and a means for moving the thrust pad in the axial direction, and as the thrust pad moves in the axial direction, The gap between the tapered surfaces of the sleeve bearing surface and the outer circumferential surface of the rotating shaft can be adjusted.

The concept behind the development of the present invention is as follows with reference to FIG.

FIG. 3 is a characteristic diagram showing the relationship between the shaft rotation speed, critical speed, and amplitude.

Regarding the startup characteristics of an overhung type high-speed rotating body, FIG. 3(a) shows the eigenvalue N6. of critical speed with respect to shaft rotation speed N (horizontal axis). (vertical axis), and the amplitude related to the vibration characteristics at startup corresponding to the eigenvalues shown in (a) is shown in Figure 3 (b).
).

In addition, the black circle dotted in Fig. 3(a) is the eigenvalue N of the critical speed. 10. N. , 2. N. , 3. N. , 4, the dotted white circle indicates the rated operating speed N, .

When the critical speed at startup is exceeded, the amplitude becomes large, but when the bearing gap is larger at the time of startup, the magnitude of this transient amplitude is reduced.

Furthermore, at startup, the bearing gap tends to become small temporarily due to thermal reasons, so it is preferable to keep the bearing gap large at startup.

One possible way to make the bearing gap variable is to make the shaft and bearing tapered. For example, if the taper is set to 1150, the rotating shaft will be connected to the bearing,
If you move 5Io111, 5 x 1750 = 0.1 m
The gap of m can be varied. This means that
If the shaft diameter is φ100, this means that a bearing with a gap of normally 0.15 mm can be increased to 0.25 mm+.

As a method for moving the rotating shaft relative to the bearing, the present invention considers moving the thrust bearing.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Here, FIG. 1 is a plan sectional view of a single-stage centrifugal compressor according to an embodiment of the present invention, and FIG. 2 is a detailed sectional view of the bearing portion of FIG. 1.

In FIG. 1, 1 is a casing, 2 is a gear casing, 3 is an impeller, 4 is a pinion shaft, 5 is a pull gear, 6 and 7 are labyrinths related to shaft sealing means, 8 is a bearing, and 9 is:
This is a bearing body equipped with a movable thrust bearing 10.

The compressor shown in FIG. 1 is a gear speed increasing type single stage centrifugal compressor, and is an overhang type rotating machine in which an impeller 3 is attached to the end of a pinion shaft 4. The pinion shaft 4 is connected to the pull gear 5
It is driven by a bearing 8 and a bearing body 9, and compresses fluid by rotating the impeller 3.

The sleeve bearing surface 9a of the bearing body 9 and the outer peripheral surface 4a of the supported mating pinion shaft 4 are each formed into a tapered surface.

Details of the bearing body 9 will be explained with reference to FIG. 2.

In FIG. 2, 9-1 is a bearing housing, 9-2 is a sleeve bearing, and the sleeve bearing surface 9a is formed into a tapered surface.

The movable thrust bearing 1-0 is of the thrust pad type, and each thrust pad is provided with a hydraulic piston, and is configured as follows so that the thrust pressure receiving surface can be arbitrarily adjusted by hydraulic pressure.

Reference numeral 11 denotes a thrust pad to be in contact with the thrust collar portion 4b of the pinion shaft 4, 12 a rod integral with the thrust pad 11, 13 a piston fixed to the rod 12, and 14.15 an O related to a sealing means. The ring 16 is a hydraulic chamber formed in the bearing housing 9-1.
It is divided into two rooms, b.

Reference numeral 17 denotes a hydraulic pipe connected to the hydraulic chamber 16a side, and 18 denotes a hydraulic pipe connected to the hydraulic chamber 16b side, which is connected to a hydraulic pressure supply source (not shown).

Next, the operation of such a bearing device will be explained.
3. At the time of startup, the critical speed N2 is reached as explained in Figure 3.
,1~N. , a large amplitude occurs when exceeding 3, but
At this time, the thrust pad 11 of the movable thrust bearing 10
move in the axial direction.

Specifically, by supplying pressure oil from the hydraulic pipe 18 to the hydraulic chamber 16b and releasing the oil in the hydraulic chamber 16a to the hydraulic pipe 17, the piston 13 is slid to the right, and the thrust pad 1
'', by pushing the thrust collar portion 4b of the pinion shaft 4, the pinion shaft 4 moves axially to the right by AL from the dashed line to the solid line in FIG. Along with this,
The gap between the sleeve bearing surface 9a and the tapered surface of the outer circumferential surface 4a of the piston shaft 4, that is, the bearing gap increases from a to b.

In this way, by adjusting the bearing gap, the amplitude at startup can be kept small, and startup can be performed without the impeller 3 and casing 1 shown in FIG. 1 coming into contact with each other.

After completion of startup, pressure oil is supplied from the hydraulic pipe 17 to the hydraulic chamber 1.6a, and the oil in the hydraulic chamber 16b is released to the hydraulic pipe 18, thereby sliding the piston 13 to the left and moving the thrust pad 11 only by AL. By returning it, operation can be performed with a predetermined gap a.

According to this embodiment, since the bearing gap can be arbitrarily adjusted, the bearing characteristics can be changed and the vibration characteristics can be adjusted. In particular, in a high-speed rotating body like this example,
In centrifugal compressors, etc. that are operated above high-order critical speeds, contact between the impeller and the casing is prevented by increasing the gap at startup and reducing the transient vibration value when the critical speed is exceeded. can do.

Furthermore, after the rated operation is reached, it is possible to make adjustments to reduce the bearing gap to ensure stable operation.

In the above-mentioned embodiment, an example of a bearing device for a single-stage centrifugal compressor was explained, but the present invention is not limited to a single-stage centrifugal compressor, but can also be applied to an overhung type centrifugal blower, etc. It can be widely applied to high-speed rotating machinery where similar effects are expected.

Furthermore, the structure of the movable thrust bearing, especially the means for moving the thrust pad in the axial direction, is not limited to the shape and structure shown in Figure 2, but other shapes and structures may be adopted as long as the same effect is expected. Needless to say, it does not interfere with

〔Effect of the invention〕

As described above, according to the present invention, the bearing characteristics can be changed by arbitrarily adjusting the bearing gap. In particular, in high-speed rotating machines, the bearing gap is increased at the time of startup, and the bearing gap is increased when the critical speed is exceeded. By reducing the transient vibration value, it is possible to provide a rotating machine equipped with a movable thrust bearing that can prevent contact between the impeller and the casing.

[Brief explanation of drawings]

Fig. 1 is a plan sectional view of a single-stage centrifugal compressor according to an embodiment of the present invention, Fig. 2 is a detailed sectional view of the bearing portion of Fig. 1, and Fig. 3 is a graph showing shaft rotation speed and critical speed. FIG. DESCRIPTION OF SYMBOLS 1... Casing, 3... Impeller, 4... Pinion shaft, 4a... Outer peripheral surface, 4b... Thrust collar part, 9... Bearing body, 9-1... Bearing housing , 9-
2...Sleeve bearing, 9a...Sleeve bearing surface, 1
0... Movable thrust bearing, 11... Thrust pad, 13... Piston, 16... Hydraulic chamber, 17.18
...Hydraulic piping.

Claims (1)

[Claims] 1. The sleeve bearing surface of the bearing body that supports the rotating body and the outer circumferential surface of the supported rotating shaft are each formed into a tapered surface, and the side surface of the bearing body is provided with the thrust surface of the rotating body. A movable thrust bearing is provided, which includes a thrust pad to be brought into contact with the collar portion, and a means for moving the thrust pad in the axial direction, and as the thrust pad moves in the axial direction, the sleeve bearing surface and the outer periphery of the rotating shaft are moved. A rotating machine equipped with a movable thrust bearing, characterized in that the gap between the tapered surface and the tapered surface can be adjusted. 2. In the device described in claim 1, the means for moving the thrust pad of the movable thrust bearing includes a hydraulic chamber formed in the bearing housing of the bearing body, and a means for moving the thrust pad by sliding within this hydraulic chamber. A rotating machine equipped with a movable thrust bearing, which consists of a piston that moves in the axial direction and hydraulic piping that supplies pressure oil to its hydraulic chamber.