HK1212019B - Support device for balance correction - Google Patents

Description

Support device for balance correction

Technical Field

The present invention relates to a balance correction support device for rotatably supporting a rotating object such as a rotor of a turbo compressor using a vertical spindle equipped with a static pressure gas bearing in order to correct the balance of the rotating object rotating at a high speed.

Background

In order to eliminate an unbalance (dynamic unbalance) caused by a component tolerance at the time of manufacturing, a rotor (corresponding to a rotating object of the present application) of a turbo compressor rotating at a high speed is generally corrected by measuring an unbalance amount using a balance correcting device.

In the balance correction device, a support device (balance correction support device) is used to rotatably support the rotor by a single body using a spindle equipped with a static pressure gas bearing in order to measure the unbalance amount with high accuracy. In many cases, as disclosed in fig. 5 of patent document 1, the following structure is used: a cylindrical spindle member into which a support hole having a circular cross section at the rotational center of the rotor is fitted is used as the spindle, a static pressure gas radial bearing (composed of a radial bearing surface having discharge holes) is provided on the outer peripheral surface of the spindle member, and a static pressure gas thrust bearing (composed of a thrust bearing surface having discharge holes) is provided on the base end side of the spindle member.

With this structure, when the support hole of the rotor is fitted into the spindle, the rotor is integrally attached to the spindle. Thereafter, a compressible fluid (air; for a static pressure gas bearing) is ejected from the ejection hole of the static pressure gas thrust bearing toward the inner surface of the support hole, and a compressible fluid (air; for a static pressure gas bearing) is ejected from the ejection hole of the static pressure gas thrust bearing toward the periphery of the opening at the lower end of the support hole (the end surface of the rotor), whereby the rotor is supported so as to be rotatable while floating around the spindle.

The unbalance amount (dynamic unbalance amount) is measured as follows: the rotor in the floating state is externally applied with a rotational force, and for example, air (driving fluid) for driving is injected toward the rotor surface to rotate the rotor at a high speed, and the operation of the rotating rotor is measured by various sensors provided in the balance correction device.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-172538 (FIG. 5)

Disclosure of Invention

Problems to be solved by the invention

As a rotor support hole, a cylindrical hole having a circular cross section, that is, a hole having a circular cross section in the entire axial direction, is generally used as disclosed in patent document 1. This is to insert an end portion of a shaft combined with the rotor into the support hole and to connect the shaft and the rotor by fastening with a bolt or the like.

However, in various system fields using a turbo compressor, there are many demands for a rotor of the turbo compressor, for example, the rotor is firmly connected to a shaft, and the axial center of the rotor and the axial center of the shaft are precisely matched with each other.

Therefore, in recent years, in order to cope with the above situation, the following coupling type structure has been proposed for the rotor of the turbo compressor: the rotor and the shaft are connected by inserting the rotor and the shaft into each other, not only by a hole having a circular cross section, but also by mixing a polygonal portion. In order to realize this connection, the following structure has been studied: an inner cavity portion having a polygonal cross-sectional shape and fitted to a polygonal portion formed on the shaft is formed on an end side of the support hole of the rotor.

However, if the support hole having the polygonal inner cavity is used, there is a possibility that the unbalance amount of the rotor cannot be sufficiently measured.

That is, in general, when the unbalance amount of the rotor is measured, the portion where the rotor is supported by the static pressure gas, that is, the portion between the outer peripheral surface of the spindle and the inner surface of the support hole is filled with the compressive fluid discharged from the discharge hole of the static pressure gas bearing.

In this case, if the support hole has a circular (perfect circular) cross section, which is the same as the outer peripheral shape of the spindle, pressure fluctuation does not occur even if the rotor rotates, and therefore high measurement accuracy can be ensured. However, when the support hole has a polygonal inner cavity, unlike the case where the cross section is circular (perfect circle), the portion having the polygonal shape is pressed against the outer peripheral surface of the mandrel by the rotation (displacement) of the rotor. Due to the squeezing effect at this time, the pressure repeatedly rises and falls between the portion having the polygonal shape and the outer peripheral surface of the mandrel.

The rotor supported by the spindle oscillates due to the pressure fluctuation. Therefore, the accuracy of measuring the unbalance amount of the rotor is easily impaired. Further, there is a problem that the rotor is likely to contact the spindle, and the desired unbalance amount may not be sufficiently measured.

Accordingly, an object of the present invention is to provide a support device for balance correction capable of measuring the unbalance amount of a rotating object having a support hole formed in a polygonal shape in part with high accuracy.

Means for solving the problems

In the present invention, the support hole of the rotated body has a portion formed in a polygonal cross-sectional shape on the end side, and a release hole for releasing to the outside a pressure varying in a space between the polygonal cross-sectional shape portion and the outer peripheral surface of the mandrel in accordance with rotation of the rotated body is provided in an outer peripheral surface portion of the vertical mandrel to which the support hole of the rotated body is attached, the outer peripheral surface portion facing the polygonal cross-sectional shape portion of the support hole. (claim 1).

According to this configuration, even if a part of the support hole has a polygonal cross-sectional shape, when the unbalance amount (dynamic unbalance amount) is measured, the fluctuation in pressure generated in the space between the polygonal cross-sectional portion of the support hole and the outer peripheral surface of the mandrel is released to the outside through the release hole. Therefore, pressure fluctuations between the polygonal cross-sectional portion of the support hole and the outer peripheral surface of the mandrel, which are caused by the pressing, are suppressed, and the unbalance amount of the body to be rotated can be measured with high accuracy.

Preferably, in addition to the above object, a plurality of relief holes are provided in the outer circumferential surface of the mandrel in the circumferential direction in order to uniformly relieve a fluctuating pressure (claim 2).

Preferably, in addition to the above object, in order to facilitate release of the fluctuating pressure, the release hole uses a passage formed by a path having an inlet near the lowermost position of a space between the polygonal cross-sectional shape portion of the spindle and the outer peripheral surface of the spindle and an outlet at a point facing the outside near the static pressure gas thrust bearing surface (claim 3).

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, when the unbalance amount of the body to be rotated is measured, the fluctuation of the pressure generated in the space between the polygonal cross-sectional portion of the support hole and the outer peripheral surface of the mandrel is released to the outside through the release hole. This can suppress pressure fluctuations in the space between the polygonal cross-sectional portion of the support hole and the outer peripheral surface of the mandrel, which is mainly caused by the pressing.

Therefore, the body to be rotated, which has a polygonal support hole, can measure the unbalance amount with high accuracy. Moreover, the body to be rotated can be prevented from contacting the spindle. Further, the configuration can be simplified (claim 1).

In addition to the above-described effects, the variable pressure can be uniformly released from the space between the polygonal cross-sectional portion and the outer peripheral surface of the mandrel through the plurality of release holes, thereby providing a higher effect (claim 2).

In addition to the above effects, the release hole is formed by the shortest route, and therefore, the pressure is more easily released to the outside, resulting in a higher effect (claim 3).

Drawings

Fig. 1 is a perspective view showing a balance correction support device according to an embodiment of the present invention together with a balance correction device to which the device is applied.

Fig. 2 is a cross-sectional view showing the structure of each part of the balance correcting support device together with a state in which a rotor (a rotated body) is attached to a spindle.

3 fig. 3 3 3 is 3a 3 sectional 3 view 3 taken 3 along 3 line 3a 3- 3a 3 in 3 fig. 32 3. 3

Fig. 4 is a sectional view taken along line B-B in fig. 2.

Fig. 5 is a sectional view for explaining the operation in the space between the polygonal cross-sectional portion of the support hole and the outer peripheral surface of the spindle when the rotor rotates.

Fig. 6 is a perspective view illustrating a rotor (driven body) of the turbo compressor for measuring the unbalance amount.

Fig. 7 is a perspective view illustrating a connection structure of a polygonal portion using the rotor.

Detailed Description

The present invention will be described below based on an embodiment shown in fig. 1 to 7.

Fig. 1 shows a schematic configuration of a balance correction device for measuring an unbalance amount (dynamic unbalance amount) of a rotating object, for example, a rotor 1 of a turbo compressor (here, for example, a compressor rotor), and in the figure, for example, reference numeral 2 denotes a substrate of the device, reference numeral 3 denotes a frame body erected on an upper surface of the substrate 2, and reference numeral 4 denotes a vibration bridge disposed in front of the frame body 3.

Each part of the vibration bridge 4 is coupled to a plurality of support spring members 5a protruding from the front surface of the frame body 3 and a support spring member 5b (only a part of which is shown) protruding from the upper surface of the substrate 2, and supports the entire vibration bridge 4 so as to be displaceable in the left-right direction. The support arm 6 extends in a strip shape from the front of the vibrating bridge 4. A support device 10 (corresponding to the balance correcting support device of the present invention) for supporting the rotor 1 of the turbo compressor is attached to the tip end portion of the band-shaped support arm 6.

Incidentally, various sensors 8 for detecting vibrations transmitted to the vibration bridge 4 are provided on the sides of the vibration bridge 4, and a pair of ejection heads 9 (rotational force applying portions) for ejecting compressed air for rotating the rotor 1 are provided around the support device 10. In fig. 1, reference numeral 8a denotes a mounting member for mounting various sensors 8 on the substrate 2, and reference numeral 9a denotes a mounting member for mounting the head unit 9 on the substrate 2.

The support device 10 has the following structure: the rotor 1 (single body) is rotatably supported by a static pressure gas bearing using a vertical spindle 11. The structure of the support device 10 is shown in fig. 2.

Here, before the description of the structure of the support device 10, the rotor 1 as a member to be measured will be described. As shown in fig. 6, for example, the rotor 1 includes a rotor body 20 in which a plurality of blades 1a are formed on a disc-shaped base surface portion 20 a. The rotor body 20 includes a cylindrical boss portion 21 formed at a central portion of the base surface portion 20 a. The rotary shaft center portion of the rotor body 20 and the boss portion 21 of the base surface portion 20a have a support hole 22 having a circular cross section and linearly penetrating these portions. A shaft 23 having a circular cross section and combined with the rotor 1 is fitted into the support hole 22. Specifically, the end of the shaft 23 is inserted into the support hole 22, and the inserted end is fixed by a fixing member, for example, a nut member (not shown), so that the rotor 1 is coupled to the receiving portion 23a that receives the end of the boss portion 21, thereby forming a rotor assembly that is an assembly in which the rotor 1 is assembled.

Here, the shaft 23 and a part of the support hole 22 for connecting the rotor 1 and the shaft 23 are polygonal (for example, for firm connection and high-precision centering).

That is, the support hole 22 having a circular-cross-section inner cavity portion as a whole from one end to the other end of the rotor 1 and the shaft 23 having a circular-cross-section corresponding to the support hole 22 are generally used, but here, as shown in fig. 6 and 7, for example, the inner surface in the boss portion 21 which becomes a part of the support hole 22, specifically, the base end of the support hole 22 has another polygonal cross-sectional shape larger than the circular-cross-section inner cavity, and here, for example, the inner surface 26a has a triangular shape, and the inner side of the inner surface 26a is a triangular inner cavity portion 26. The shaft 23 has a triangular flange 27, for example, which is fitted into the triangular cavity 26. That is, the rotor 1 and the shaft 23 are coupled together using a structure in which the triangular inner cavity 26 and the flange 27 are fitted.

The support device 10 of fig. 1 and 2 has a structure for stably supporting the rotor 1 by forming a part of the support hole 22 into a polygonal shape.

The parts of the support device 10 will be described with reference to fig. 1 and 2. Reference numeral 11 is the spindle described above. The spindle 11 is formed of a cylindrical spindle member. The spindle member is erected on the upper surface of the distal end portion of the support arm 6, and the rotor 1 is mounted from above the spindle 11.

That is, the mandrel 11 has, in order from the lower end: the installation base 30 fixed to the support arm 6, the disk-shaped portion 31 receiving the lower end (end of the boss portion 21) of the rotor 1, and the cylindrical portion 32 capable of fitting into the rotor 1 extend from the support arm 6 in the vertical direction by a predetermined amount. Specifically, the portion of the cylindrical portion 32 where the rotor body 20 on the front end side is disposed (except for the boss portion 21) is formed by a column portion 32a having a circular cross section that matches the shape of a small-diameter hole portion 22d occupying most of the support hole 22 of the rotor body 20. The portion where the boss portion 21 on the base end side is disposed is formed into a column portion 32b having a larger diameter than the column portion 32a in conformity with the shape of the step portion 22a of the support hole 22 as shown in fig. 3. In particular, the portion corresponding to the triangular inner cavity portion 26 (inner surface 26a) is formed into a column portion 32c (smaller in diameter than the inner surface 26a) having a smaller diameter than the column portion 32b as shown in fig. 4, and the rotor 1 can be attached around the spindle 11 by merely inserting the rotor 1 into the spindle 11 from the end (base end) of the support hole 22 as shown in fig. 2 without being affected by the presence or absence of the triangular inner cavity portion 26.

Further, on the outer peripheral surfaces of the column parts 32a, 32b of the mandrel 11, static pressure gas radial bearing surfaces 34b having a plurality of discharge holes 34a are provided, respectively, and the static pressure gas radial bearings 34 receiving the inner surfaces of the support holes 22 are formed. A static pressure gas thrust bearing surface 35b having a plurality of discharge holes 35a is provided on the upper surface of the disk-shaped portion 31 around the axial center in accordance with the position of the end of the boss portion 21, and a static pressure gas thrust bearing 35 is formed at this portion, and the static pressure gas thrust bearing 35 receives the end surface of the boss portion 21 (the periphery of the opening of the support hole 22) which becomes the lower end of the rotor 1.

As shown in fig. 2, the discharge port 34a is connected to an external gas supply device 37 for hydrostatic bearing through a passage 36a having various diameters formed along the axial center portion of the spindle 11 and a relay passage 36b formed inside the support arm 6. The discharge hole 35a is connected to the gas supply device for hydrostatic bearing 37 via a passage 38a formed in the disk-shaped portion 31 and a relay passage 38b formed inside the support arm 6. Thus, the compressive fluid, for example, air, supplied from the gas supply device 37 for hydrostatic bearing is ejected from the ejection holes 34a and 35a, and the rotor 1 is received (supported) by the hydrostatic gas bearings 34 and 35 in the radial direction and thrust direction, whereby the entire rotor 1 can be supported rotatably while floating up by a predetermined amount around the spindle 11.

When air is blown from the pair of head portions 9 to the rotor 1 in the floating state, the rotor 1 rotates at a high speed, and the operation (vibration) at this time is detected by the various sensors 8 via the support arm 6 and the vibration bridge 4, and the unbalance amount of the rotor 1 is measured.

As shown in fig. 1, 2, and 4 (cross section B-B in fig. 2), release holes 38 are provided in the outer peripheral surface of the column portion 32c of the outer peripheral surface of the spindle 11, the column portion facing the triangular inner cavity 26 of the rotor 1 (corresponding to the polygonal cross-sectional portion of the present application). The release holes 38 are provided in plurality, here 9, at equal intervals in the circumferential direction of the mandrel 11.

Any of the relief holes 38 is formed, as shown in fig. 2, by a small-diameter J-shaped passage 39 in which an inlet 39a opens into a space formed between the pillar portion 32c and the inner surface 26a, and an outlet 39b opens out of the space. For example, the inlet 39a of the passage 39 opens at the outer peripheral surface portion of the column portion 32c near the lowermost position of the space between the column portion 32c and the inner surface 26a, and the outlet 39b opens at a point facing the outside, for example, a point near the bearing surface 35b of the end surface of the disk-shaped portion 31 near the static pressure gas thrust bearing surface 35b, so that the passage 39 is formed by the shortest route. The structure is as follows: the pressure fluctuation, particularly, the increased pressure generated in the space between the inner surface 26a of the triangular shape and the outer peripheral surface of the column portion 32c having a circular cross section when the rotor 1 rotates is released to the outside by the passage 39 formed by the shortest route.

Next, the release of the pressure fluctuation will be described.

First, when measuring the unbalance amount of the rotor 1, as shown in fig. 2, the support hole 22 of the rotor 1 is fitted into the spindle 11 standing in the vertical direction, and the rotor 1 is mounted on the spindle 11. Here, the hole portion 22d of the rotor 1 is disposed in a column portion 32a (including the upper stage static pressure gas radial bearing 34) having a circular cross section of the spindle 11, the stepped portion 22a of the rotor 1 is disposed in a column portion 32b (including the lower stage static pressure gas radial bearing 34), and the triangular inner cavity portion 26 of the rotor 1 is disposed in a column portion 32 c. Further, the end of the boss portion 21 of the rotor 1 is disposed on the static pressure type gas thrust bearing surface 35 b.

Thereafter, the compressed air (compressible fluid) from the gas supply device 37 for hydrostatic bearing is ejected from the ejection holes 34a and 35a by a predetermined amount. Then, as indicated by arrows in fig. 2, the air ejected from the ejection holes 34a flows into the space between the radial static pressure gas bearing surface 34b and the inner surface of the hole portion 22d and the inner surface of the stepped portion 22a, and the rotor 1 is rotatably supported around the spindle 11 by the air flow flowing into the space between the radial static pressure gas bearing surface 34b and the inner surface of the hole portion 22d and the inner surface of the stepped portion 22a, and the air ejected from the ejection holes 35a pushes up the boss portions 21 and flows into the space between the thrust static pressure gas bearing surface 35b and the end surfaces of the boss portions 21, as indicated by arrows in fig. 2, thereby floating the entire rotor 1 by a predetermined amount. That is, the rotor 1 is supported rotatably by the spindle 11 while floating by a predetermined amount.

Thereafter, when air is blown from the discharge holes 9b (only a part of which is shown in fig. 1) of the pair of head portions 9 to the blades 1a of the floating rotor 1, the rotor 1 rotates at a high speed around the spindle 11. The motion (vibration) of the rotor 1 at this time is transmitted to various sensors 8 via the support arms 6 and the vibration bridges 4, and the unbalance amount of the rotor 1 is measured by the detection of the sensors 8.

At this time, the space (inner cavity portion 26) between the triangular inner surface 26a of the rotor 1 and the column portion 32c of the spindle 11 is filled with air discharged from the discharge holes 34a, 35a of the hydrostatic gas bearings 34, 35.

Here, although there is no problem because the conventional rotor and spindle are combined with each other by a circular shape, the end portion of the support hole 22 of the rotor 1 is determined to be polygonal, here triangular, and therefore, as the rotor 1 rotates, a compression occurs between the boss portion 21 having the triangular inner cavity portion 26 and the column portion 32c having a circular cross section. Therefore, in the space between the triangular inner surface 26a and the column portion 32c having a circular cross section, pressure rise and pressure fall due to the squeezing effect occur repeatedly in the space such that the front pressure rises in the rotational direction and the rear pressure falls in the rotational direction of the triangular inner surface 26a displaced as shown in fig. 5.

The pressure fluctuation causes the rotor 1 to oscillate (ハンチング oscillation). If this is done, the rotor 1 is affected by the oscillation, and the accuracy of measuring the unbalance amount of the rotor 1 is impaired. However, since the release hole 38 for releasing the pressure varying in the space between the triangular inner surface 26a and the column portion 32c having a circular cross section to the outside is provided in the mandrel 11, the pressure variation occurring in the space, that is, the increased pressure, is released to the outside (outside) of the space through the release hole 38 as shown by the arrow in fig. 2 and 5. The reduced pressure is compensated by air from the hydrostatic gas bearings 34, 35.

This suppresses pressure fluctuations between the polygonal cross-sectional portion of the support hole 22 (the triangular inner cavity 26) and the outer circumferential surface of the mandrel 11 having a circular cross-section, which is a factor of impairing accuracy.

Therefore, the unbalance amount of the rotor 1 (the rotated body) can be measured with high accuracy. Further, the measurement accuracy can be improved only by forming the relief hole 38 in the outer peripheral surface of the spindle 11 at a point facing the polygonal cross-sectional shape portion of the support hole 22, and therefore, the configuration can be simplified. Further, the fear of the rotor 1 contacting the spindle 11 can also be avoided.

In particular, since the plurality of release holes 38 are arranged at equal intervals in the circumferential direction of the mandrel 11, the pressure fluctuations can be uniformly released to the outside, and the pressure fluctuations can be more effectively suppressed.

Further, when the relief hole 38 is formed by the shortest route, the fluctuating pressure is easily released to the outside, and therefore, the pressure fluctuation can be more effectively suppressed.

The present invention is not limited to the above embodiment, and various modifications may be made without departing from the scope of the present invention. For example, in the above-described embodiment, the polygonal portion of the support hole is a triangular inner cavity portion, but the present invention is not limited thereto, and other polygonal inner cavity portions may be used. In the above-described embodiment, 9 relief holes are provided as an example, but the number is not limited to this, and is not particularly limited as long as the effect of suppressing pressure fluctuations can be sufficiently ensured regardless of the number of relief holes being 9 or more or 9 or less. Of course, although the rotor of the turbo compressor is used in the above embodiment, the present invention is not limited to this, and may be applied to any rotating object as long as the unbalance amount needs to be measured.

Description of the reference numerals

1 rotor (rotated body)

10 support device (support device for balance correction)

11 mandrel

22 bearing hole

26 triangular inner cavity (polygonal cross-section)

26a triangular inner surface (polygonal inner surface)

34 static pressure gas radial bearing

35 static pressure gas thrust bearing

38 relief hole

39a inlet

39b outlet

Claims (3)

1. A balance correction support device is composed of the following structures: the support device for balance correction includes a rotated body having a support hole with a circular cross section at a rotation center portion and having a polygonal cross-sectional shape at an end side thereof, and a vertical spindle inserted into the support hole to mount the rotated body from a vertical direction; a static pressure gas radial bearing having an inner surface with a circular cross section for rotatably receiving the support hole on an outer peripheral surface of the mandrel, and a static pressure gas thrust bearing having an opening surrounding a lower end of the support hole on a base end side of the mandrel; the method is characterized in that a compressible fluid for a static pressure gas bearing is ejected from the static pressure gas radial bearing and the static pressure gas thrust bearing to support the rotating body rotatably while floating around the spindle, and the unbalance amount can be measured by applying a rotational force to the floating rotating body,

the support device for balance correction is characterized in that,

a release hole for releasing to the outside a pressure varying in a space between the polygonal cross-sectional shape portion and the outer peripheral surface of the mandrel in accordance with rotation of the body to be rotated is provided in an outer peripheral surface portion of the outer peripheral surface of the mandrel, the outer peripheral surface portion facing the polygonal cross-sectional shape portion of the support hole.

2. The support device for balance correction according to claim 1,

the release holes are provided in plurality in the circumferential direction on the outer circumferential surface of the mandrel.

3. The support device for balance correction according to claim 1 or 2,

the relief hole is a through hole formed by a path having an inlet near the lowermost position of a space between the polygonal cross-sectional shape portion and the outer peripheral surface of the spindle in the spindle and having an outlet at a point facing the outside near the static pressure gas thrust bearing surface.