JP2010276161A - Bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device to support the rotary shaft of a rotary machine with three or more bearings, capable of precluding such an occurrence that a change in the supporting rigidity of the rotary shaft causes the vibration characteristics of the rotary machine to change abruptly even in case a node of the vibration mode due to the operating range natural frequency lies in the position of any bearing. <P>SOLUTION: The bearing device 10 supports the radially directed load on the rotary shaft of the rotary machine with three or more bearings 5a, 5b, 5c, wherein the natural frequency of the rotary shaft 3 lying within the operating speed range of the rotary machine is used as the operating range natural frequency, and the bearing 5b lying at a node of the vibration mode or around the node due to the operating range natural frequency is formed as a negative gap bearing. The negative gap bearing is configured so as to transmit the force from the rotary shaft 3 to a stationary side member 7 of the rotary machine at all times. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bearing device that supports a radial load of a rotating shaft of a rotating machine with three or more bearings.

  A rotary machine such as a jet engine, a gas turbine, a compressor, and a supercharger has a rotary shaft that is rotationally driven and a plurality of bearings that support a radial load of the rotary shaft. For example, a rolling bearing is used as the bearing. Inside each of the bearings, there is a gap (play) in the radial direction of the rotating shaft.

  Two such bearings are usually provided for one rotating shaft. The radial load is always applied to these two bearings due to the weight or vibration of the rotating shaft.

JP 2004-1000084 A

However, when the radial load of the rotating shaft of a rotating machine is supported by three bearings, the rotating shaft is supported by only two bearings at a specific operating rotational speed, and the remaining bearings have a radial load. It may not work. In this case, the support rigidity of the rotating shaft changes, and the vibration characteristics of the rotating machine change abruptly. Specifically, it is as follows.
First, let the natural frequency of the rotating shaft within the operating rotational speed range of the rotating machine be the operating region natural frequency. In the rotating shaft, when the node of the vibration mode by the operating region natural frequency is at the axial position of the bearing, the load may hardly be applied to the bearing from the rotating shaft at the operating region natural frequency. In this case, since the rotating shaft is supported by the other two bearings, the support rigidity for supporting the radial load of the rotating shaft changes, and the vibration characteristics of the rotating machine change abruptly. The same applies when the radial load of the rotating shaft is supported by four or more bearings.

  The inventor of the present invention has created the present invention by paying attention to the above-mentioned problems. That is, an object of the present invention is to provide a bearing device that supports a rotating shaft with three or more bearings, and the support rigidity of the rotating shaft changes even when the vibration mode node due to the natural frequency in the operating range is at the position of the bearing. It is to prevent the vibration characteristics of the rotating machine from changing abruptly.

In order to achieve the above object, according to the present invention, there is provided a bearing device for supporting a radial load of a rotating shaft of a rotating machine by three or more bearings,
The natural frequency of the rotating shaft within the operating rotational speed range of the rotating machine is the natural frequency of the operating region,
The bearing at or near the node of the vibration mode according to the natural frequency of the operating region is configured as a negative clearance bearing,
The negative gap bearing is configured to always transmit force from the rotating shaft to the stationary member of the rotating machine.

  In the above-described bearing device according to the present invention, the axial position serving as a node of the vibration mode of the rotating shaft at the operating region natural frequency or a bearing near the axial position is configured as a negative clearance bearing, and the negative clearance bearing Is configured to always transmit force from the rotating shaft to the stationary side member of the rotating machine, so the negative clearance bearing supports the radial load from the rotating shaft even at the operating frequency range. To do. Therefore, it is possible to prevent the support rigidity of the rotating shaft from changing and the vibration characteristics of the rotating machine from changing suddenly.

  The negative clearance bearing described above may be configured as follows. That is, the negative clearance bearing has an inner ring attached to the rotating shaft, an outer ring attached to the stationary side member of the rotating machine, and a plurality of rolling elements provided between the inner ring and the outer ring. The outer peripheral surface and the inner peripheral surface of the outer ring are circular when viewed from the axial direction of the rotating shaft, and the gap between the outer peripheral surface and the inner peripheral surface is smaller than the dimensions of the rolling elements.

  Moreover, you may comprise the above-mentioned negative clearance bearing as follows. That is, the negative clearance bearing has an inner ring attached to the rotating shaft, an outer ring attached to the stationary side member of the rotating machine, and a plurality of rolling elements provided between the inner ring and the outer ring. At least one of the outer peripheral surface and the inner peripheral surface of the outer ring is non-circular when viewed from the axial direction of the rotary shaft, and at least partially in the circumferential direction around the axis of the rotary shaft, The clearance between the surface and the inner peripheral surface is smaller than the size of the rolling element.

  According to the above-described present invention, in the bearing device that supports the rotating shaft with three or more bearings, even when the vibration mode node due to the natural frequency of the operating region is at the position of the bearing, the supporting rigidity of the rotating shaft changes, It is possible to prevent the vibration characteristics of the rotating machine from changing suddenly.

It is a schematic diagram which shows the structure of the bearing apparatus by embodiment of this invention. (A) shows the amplitude of the first vibration mode in the rotating shaft of FIG. 1, (B) shows the amplitude of the second vibration mode in the rotating shaft of FIG. 1, and (C) shows the amplitude of FIG. The amplitude of the 3rd vibration mode in a rotating shaft is shown. It is an AA arrow line view of FIG. 1, and shows the structural example of a negative clearance bearing. (A) is an AA arrow view of FIG. 1, shows another configuration example of the negative gap bearing, (B) is an AA arrow view of FIG. Another example of the configuration will be described. It is a schematic diagram which shows the structure of the bearing apparatus by other embodiment of this invention. (A) shows the amplitude of the first vibration mode in the rotating shaft of FIG. 5, (B) shows the amplitude of the second vibration mode in the rotating shaft of FIG. 5, and (C) shows the amplitude of FIG. The amplitude of the 3rd vibration mode in a rotating shaft is shown.

  The best mode for carrying out the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a schematic diagram showing a configuration of a bearing device 10 according to an embodiment of the present invention. The bearing device 10 supports the radial load of the rotating shaft 3 of the rotating machine with three or more bearings (in FIG. 1, three bearings 5a, 5b, and 5c). The rotating machine has a rotating shaft 3 that is driven to rotate, and is, for example, a jet engine, a gas turbine, a compressor, a supercharger, or the like. In the present application, a member that is fixed to the rotating shaft 3 and rotates integrally with the rotating shaft 3 is also included in the rotating shaft 3. In FIG. 1, members (for example, a rotating disk, a moving blade, a turbine blade, a compressor blade, etc.) fixed to the rotating shaft 3 are omitted. Each bearing 5a, 5b, 5c may be a rolling bearing. In FIG. 1, each bearing 5a, 5b, 5c is attached to a stationary member 7 that is provided in a rotating machine and does not rotate.

  Define terms. In the present application, the operating region natural frequency is a natural frequency of the rotating shaft 3 within the operating rotational speed range of the rotating machine. For example, when m is an integer of 2 or more and the natural frequency of the first vibration mode to the mth vibration mode is within the operating rotational speed range of the rotating machine, the first vibration mode to the mth vibration mode Each natural frequency of the vibration mode is an operating region natural frequency. The operating rotational speed range is a range of the rotational speed (rpm) of the rotating shaft 3 in one minute, for example, a range from zero to a predetermined value. The natural frequency is the resonance frequency of the rotating shaft 3. When forced vibration with a resonance frequency is applied to the rotating shaft 3, the amplitude of the rotating shaft 3 increases and the rotating shaft 3 may be damaged.

  According to this embodiment, the node 5a, 5b or 5c in the vicinity of the vibration mode node of the rotating shaft 3 at the operating region natural frequency is configured as a negative clearance bearing. The negative clearance bearing is configured to apply a preload to the stationary side member 7 and the rotating shaft 3 of the rotating machine. That is, the negative clearance bearing always applies a force to the stationary member 7 and the rotating shaft 3 of the rotating machine so as to transmit the force from the rotating shaft 3 to the stationary member 7.

2A shows a broken curve of the amplitude of the rotating shaft 3 at the natural frequency of the first vibration mode in the bearing device 10 of FIG. 1, and FIG. 2B shows the bearing device 10 of FIG. The amplitude of the rotating shaft 3 according to the natural frequency of the second vibration mode is shown by a broken line. FIG. 2C shows the rotating shaft 3 according to the natural frequency of the third vibration mode in the bearing device 10 of FIG. The amplitude of is shown by a broken curve. In this example, for the sake of simplicity, the operating range natural frequency of the rotating shaft 3 in FIG. 1 includes the natural frequency of the first vibration mode, the natural frequency of the second vibration mode, and the natural frequency of the third vibration mode. Suppose that there is a frequency.
As shown in FIG. 2, in the rotating shaft 3, the node of the natural frequency of the second vibration mode is at the position of the bearing 5b. Therefore, this bearing 5b is configured as a negative clearance bearing.

  3 is an AA arrow view of FIG. 1 and shows a configuration example of the negative clearance bearing in a state assembled to the rotating shaft 3 and the stationary side member 7. As shown in FIG. 3, the negative clearance bearing is provided between the inner ring 9 attached to the rotating shaft 3, the outer ring 11 attached to the stationary side member 7 of the rotating machine, and between the inner ring 9 and the outer ring 11. Rolling elements 13. The outer peripheral surface 9a of the inner ring 9 and the inner peripheral surface 11a of the outer ring 11 are circular (that is, a perfect circle) when viewed from the axial direction of the rotary shaft 3, and the outer peripheral surface in the radial direction with respect to the axial direction. The gap between 9a and the inner peripheral surface 11a is smaller than the dimension of the rolling element 13, whereby the negative gap bearing always transmits force from the rotating shaft 3 to the stationary side member 7 of the rotating machine. In this way, each rolling element 13 applies a force to the stationary member 7 and the rotating shaft 3 so as to always transmit a force from the rotating shaft 3 to the stationary member 7 via the inner ring 9 and the outer ring 11. . In other words, the inner ring 9 and the outer ring 11 always apply a preload to each rolling element 13. The inner ring 9 may be fixed to the rotary shaft 3 and the outer ring 11 may be fixed to the stationary member 7. The rolling element 13 is a ball or a roller. The preload is set so that the decrease in the life of the bearing 5b can be suppressed within an allowable range.

  In the configuration example of FIG. 3, the gap between the inner ring 9 and the outer ring 11 is smaller than the size of the rolling element 13 in the radial direction of the rotating shaft 3. Therefore, in FIG. 3, each rolling element 13 always exerts a force between the inner ring 9 and the outer ring 11.

  Such a negative clearance bearing is assembled as follows, for example. First, the outer ring 11 is assembled to the stationary member 7 in advance. In this state, the outer ring 11 and the stationary member 7 are expanded by heating. As the outer ring 11 and the stationary member 7 expand, the inner diameter of the outer ring 11 increases. In this state, the rolling element 13 is disposed between the inner ring 9 and the outer ring 11 by passing the inner ring 9 and the rolling element 13 assembled to the rotating shaft 3 together with the rotating shaft 3 through the outer ring 11. At this time, since the gap between the outer peripheral surface 9a and the inner peripheral surface 11a is increased by the expansion, the rolling element 13 can be disposed between the inner ring 9 and the outer ring 11 without resistance. Thereafter, when the outer ring 11 and the stationary member 7 are cooled and the expansion is stopped, the inner ring 9 and the outer ring 11 apply a preload to the rolling elements 13 as described above. In addition, you may assemble the negative clearance bearing of FIG. 3 with another method.

4 (A) and 4 (B) are AA arrow views of FIG. 1, and show another configuration example of the negative clearance bearing in a state assembled to the rotating shaft 3 and the stationary side member 7. The configuration examples in FIGS. 4A and 4B are the same as the configuration example in FIG. 3 except for the points described below. 4A and 4B, in the negative clearance bearing, at least one of the outer peripheral surface 9a of the inner ring 9 and the inner peripheral surface 11a of the outer ring 11 (in the example of FIG. 4, the inner peripheral surface 11a) is When viewed from the axial direction of the rotary shaft 3, it is non-circular (in FIG. 4A, a shape formed of a plurality of arcs, and in FIG. 4B, an ellipse). Further, at least partially in the circumferential direction around the axis of the rotating shaft 3 (in FIG. 4A, at the circumferential locations 17, 18, 19 and in FIG. 4B, at the circumferential locations 17, 18). The radial gap between the outer peripheral surface 9a and the inner peripheral surface 11a is smaller than the radial dimension of the rolling element 13, so that the negative gap bearing is always stationary from the rotary shaft 3 to the rotating machine. Force is transmitted to the side member 7. Thus, in FIG. 4 (A), the rolling elements 13 located in the circumferential locations 17, 18, and 19 exert a force between the inner ring 9 and the outer ring 11, and in FIG. 4 (B), in the circumferential direction. The rolling elements 13 located at the locations 17 and 18 exert a force between the inner ring 9 and the outer ring 11, whereby the negative clearance bearing always moves from the rotating shaft 3 to the stationary side member 7 of the rotating machine. Transmit power.
Regardless of the circumferential position of each rolling element 13, one or more rolling elements 13 are always located at circumferential locations 17, 18, and 19 in FIG. 4A, and in FIG. Located in the directional locations 17, 18, the one or more rolling elements 13 thus always exert forces between the inner ring 9 and the outer ring 11.

  4A and 4B may be assembled by the same method as the assembly of the negative clearance bearing of FIG. 3 described above, or may be assembled by other methods.

  In addition, the other structure of the negative clearance bearing demonstrated based on FIG. 3 or FIG. 4 may be the same as the structure of a general rolling bearing. For example, the rolling elements 13 are held at intervals in the circumferential direction by a retainer (not shown).

  In the bearing device 10 according to the above-described embodiment of the present invention, the bearing 5a, 5b, or 5c at or near the axial position serving as a node of the vibration mode of the rotating shaft 3 at the operating region natural frequency is negative. Since it is configured as a clearance bearing, and the negative clearance bearing is configured to apply a preload to the stationary side member 7 and the rotating shaft 3 of the rotating machine, the negative clearance bearing has a natural frequency at the operating region. Also, a load acts from the rotating shaft 3. Therefore, it is possible to prevent the support rigidity of the rotating shaft 3 from changing and the vibration characteristics of the rotating machine from changing suddenly.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention as follows.

  The negative clearance bearing used in the present invention is not limited to the configuration shown in FIGS. For example, in FIG. 4, when viewed from the axial direction, the outer peripheral surface 9a of the inner ring 9 is circular and the inner peripheral surface 11a of the outer ring 11 is non-circular. However, the outer peripheral surface 9a of the inner ring 9 is non-circular, The outer peripheral surface 11a of 11 may be circular.

  In the present invention, the rolling bearings (for example, the bearings 5a, 5b, 5c) positioned at the nodes of the operating range natural frequencies are configured as negative clearance bearings for each operating range natural frequency. Two or more bearings may be used. One example will be described with reference to FIGS.

FIG. 5 shows a case where the positions of the bearings 5a, 5b, and 5c in the bearing device 10 are different from those in FIG. 6A shows a broken curve of the amplitude of the rotating shaft 3 at the natural frequency of the first vibration mode in the bearing device 10 of FIG. 5, and FIG. 6B shows the bearing device 10 of FIG. The amplitude of the rotating shaft 3 according to the natural frequency of the second vibration mode is shown by a broken line. FIG. 6C shows the rotating shaft 3 according to the natural frequency of the third vibration mode in the bearing device 10 of FIG. The amplitude of is shown by a broken curve. In this example, for the sake of simplicity, the natural frequency of the operating range of the rotary shaft 3 in FIG. 5 includes the natural frequency of the first vibration mode, the natural frequency of the second vibration mode, and the natural frequency of the third vibration mode. Suppose that there is a frequency.
As shown in FIG. 6, in the rotary shaft 3, the node of the natural frequency of the second vibration mode is at the position of the bearing 5b, and the node of the natural frequency of the third vibration mode is at the position of the bearing 5a. Accordingly, these bearings 5b and 5a are configured as the above-described negative clearance bearings.

3 rotating shaft, 5a, 5b, 5c bearing, 7 stationary side member,
9 inner ring, 9a outer peripheral surface of inner ring, 10 bearing device,
11 outer ring, 11a inner peripheral surface of outer ring, 13 rolling element,

Claims (3)

A bearing device for supporting a radial load of a rotating shaft of a rotating machine with three or more bearings,
The natural frequency of the rotating shaft within the operating rotational speed range of the rotating machine is the natural frequency of the operating region,
The bearing at or near the node of the vibration mode according to the natural frequency of the operating region is configured as a negative clearance bearing,
The negative gap bearing is configured to always transmit force from the rotating shaft to a stationary member of the rotating machine. The negative clearance bearing has an inner ring attached to the rotating shaft, an outer ring attached to the stationary side member of the rotating machine, and a plurality of rolling elements provided between the inner ring and the outer ring,
The outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring are circular when viewed from the axial direction of the rotary shaft, and the gap between the outer peripheral surface and the inner peripheral surface is a dimension of the rolling element. The bearing device according to claim 1, wherein the bearing device is smaller. The negative clearance bearing has an inner ring attached to the rotating shaft, an outer ring attached to the stationary side member of the rotating machine, and a plurality of rolling elements provided between the inner ring and the outer ring,
At least one of the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring is non-circular when viewed from the axial direction of the rotating shaft, and at least partially in the circumferential direction around the axis of the rotating shaft. The bearing device according to claim 1, wherein a gap between the outer peripheral surface and the inner peripheral surface is smaller than a dimension of the rolling element.

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