SLEEVE FOR ROTOR AND ROTOR

Abstract

A sleeve for a rotor is provided, the sleeve comprising a through-hole for fitting a shaft having a small-diameter shaft section and a large-diameter shaft section, which differ in their outer diameter dimension and are arranged side by side along an axis. The through-hole comprises a small-diameter hole section and a large-diameter hole section arranged at distances from each other along the axis and each fitted in close contact with the small-diameter shaft section and the large-diameter shaft section, respectively, as well as an intermediate hole section arranged between the small-diameter hole section and the large-diameter hole section.The sleeve includes a groove located on an inner surface of the small-diameter and large-diameter hole sections, extending axially from intermediate points between these sections to the intermediate hole section. The sleeve includes a hydraulic pressure supply port opening on an inner surface of the intermediate hole section or the groove.

Description

{Technical field}

[0001] The present disclosure relates to a sleeve for a rotor and a rotor. {State of the art}

[0002] A rotor is known that includes a shaft having a step and a sleeve fitted onto the shaft (see, for example, Patent Literature 1). The sleeve has a hollow portion arranged to cover the step portion and a hydraulic pressure supply hole communicating with the hollow portion.

[0003] During rotor assembly, the sleeve is shrink-fitted onto the shaft. Accordingly, the sleeve and shaft are secured together by high contact pressure on two sides that enclose the cavity in the axial direction. During rotor disassembly, an operator directs hydraulic pressure from the hydraulic pressure supply hole into the cavity to separate the sleeve from the shaft.

[0004] Because the contact pressure between the sleeve and the shaft is high, high hydraulic pressure must be applied to the cavity to separate the sleeve from the shaft. When the sleeve expands radially due to the application of hydraulic pressure, the contact pressure between the sleeve and the shaft is reduced, thus reducing the static friction force between them. Therefore, the sleeve separates from the shaft at the moment the axial force generated by the hydraulic pressure exceeds the static friction force. {Reference list}{Patent specifications}

[0005] {PTL 1} Japanese Unexamined Utility Model Application Publication No. Hei 5-26202 {Explanation of the invention}{Technical problem}

[0006] In this case, because there are cases where the sleeve quickly separates from the shaft under high hydraulic pressure in the hollow section, a countermeasure is required to prevent the separated sleeve or shaft from quickly popping out. Therefore, it is necessary to prevent the sleeve from quickly separating from the shaft even under high hydraulic pressure. {Solution to the task}

[0007] One aspect of the present disclosure is a sleeve for a rotor, the sleeve comprising a through hole for fitting a shaft having a small-diameter shaft portion and a large-diameter shaft portion that are different in outer diameter dimension and arranged side by side in an axial direction, wherein: the through hole includes a small-diameter hole portion and a large-diameter hole portion that are arranged at positions spaced apart from each other in the axial direction and are respectively fitted into the small-diameter shaft portion and the large-diameter shaft portion in close contact, and an intermediate hole portion that forms an airtight chamber supplied with hydraulic pressure between the small-diameter hole portion and the large-diameter hole portion;and one or more recesses isolated from the intermediate hole portion are provided on an inner surface of the large-diameter hole portion; {Brief description of the drawings} { Fig. 1} Fig. 1 is a longitudinal sectional view illustrating a rotor according to a first embodiment of the present disclosure. { Fig. 2} Fig. 2 is a longitudinal sectional view illustrating a sleeve according to the first embodiment of the present disclosure, which supports the rotor in Fig. 1 forms. { Fig. 3} Fig. 3 is a longitudinal sectional view illustrating a state in which an airtight chamber is formed at a position A where a shaft and the sleeve in the rotor are in Fig. 1 are attached, is subjected to hydraulic pressure. { Fig. 4} Fig. Fig. 4 is a longitudinal sectional view illustrating a state in which the shaft is moved to a position B with respect to the sleeve by increasing the hydraulic pressure from the state in Fig. 3 is increased. { Fig. 5} Fig. 5 is a longitudinal sectional view illustrating a state in which the shaft is displaced relative to the sleeve from the state in Fig. 4 is moved to a position C. { Fig. 6} Fig. 6 is a longitudinal sectional view illustrating a state in which the shaft is displaced relative to the sleeve from the state in Fig. 5 is moved to a position D. { Fig. 7} Fig. Figure 7 is a graph showing the changes in hydraulic pressure and volume of the airtight chamber with respect to the positions of the rotor in the Fig. 3 to 6 illustrates { Fig. 8} Fig. 8 is a longitudinal sectional view illustrating a rotor according to a second embodiment of the present disclosure. { Fig. 9} Fig. 9 is a longitudinal sectional view of some parts showing a modification of a large diameter hole portion in the rotors in the Fig. 1 and Fig. 8 illustrates. { Fig. 10} Fig. 10 is a longitudinal sectional view of some parts showing a further modification of the large diameter hole portion in the rotors in the Fig. 1 and Fig. 8 illustrates. { Fig. 11} Fig. Figure 11 is a graph showing the changes in hydraulic pressure and volume of the airtight chamber with respect to the locations of the rotor in the cases in Fig. 9 and Fig. 10 illustrates. { Fig. 12} Fig. Figure 12 is a side cross-sectional view of a sleeve showing a modification of the recesses in the sleeve in Fig. 2 illustrates. {Description of the embodiments}

[0008] A sleeve 4 and a rotor 1 according to a first embodiment of the present disclosure will be described below with reference to the drawings.

[0009] The rotor 1 according to this embodiment is, for example, a rotor for a built-in motor in which a stator thereof is integrated into an industrial machine. As shown in Fig. 1, the rotor 1 comprises a main shaft (shaft) 2 and a cylindrical sleeve (sleeve for a rotor) 4 having a through hole 3 for fitting the main shaft 2.

[0010] As in Fig. 1, the main shaft 2 comprises a small-diameter shaft portion 5 and a large-diameter shaft portion 6 arranged side by side in a direction along an axis O. Furthermore, the main shaft 2 comprises a stop surface 7 which abuts against an end surface of the sleeve 4 on the side of the large-diameter shaft portion 6 in the direction along the axis O.

[0011] The small-diameter shaft section 5 and the large-diameter shaft section 6 each have a smooth cylindrical outer surface, and an outer diameter dimension D1 of the large-diameter shaft section 6 is larger than an outer diameter dimension D2 of the small-diameter shaft section 5. A step 8 is formed between the small-diameter shaft section 5 and the large-diameter shaft section 6, the height of which corresponds to a difference ΔD / 2 = (D1-D2) / 2 of the outer diameter dimensions (radii) of the two components.

[0012] An iron core 9 is shrink-fitted to an outer surface of the sleeve 4. A side ring 10 is fixed to each of the two ends of the iron core 9 in the axial direction O. The side ring 10 has an outer diameter dimension larger than that of the iron core 9 and protects the iron core 9 from contacting an inner surface of the stator when the rotor 1 is inserted into the stator. Furthermore, the side ring 10 includes a plurality of screw holes (not shown) for attaching masses for adjusting the balance of the rotor 1.

[0013] The through hole 3 of the sleeve 4 includes, on one end side in the axial direction O, a large-diameter hole portion 11 for fitting the large-diameter shaft portion 6 of the main shaft 2 in a close contact state. Furthermore, the through hole 3 of the sleeve 4 includes, on the other end side in the axis O direction, a small-diameter hole portion 12 for fitting the small-diameter shaft portion 5 of the main shaft 2 in a close contact state. Furthermore, the small-diameter hole portion 12 and the small-diameter shaft portion 5, and the large-diameter hole portion 11 and the large-diameter shaft portion 6 are each closely fitted to each other.In this embodiment, the small diameter hole portion 12 and the large diameter hole portion 11 each have a cylindrical inner surface and also have length dimensions in the direction along the axis O that are approximately equal to each other.

[0014] Furthermore, the through hole 3 of the sleeve 4 includes an intermediate hole portion 13 at a location located between the small-diameter hole portion 12 and the large-diameter hole portion 11 in the direction along the axis O. In this embodiment, the intermediate hole portion 13 has a length dimension in the direction along the axis O that is larger than those of the small-diameter hole portion 12 and the large-diameter hole portion 11, and an inner diameter dimension that is larger than that of the large-diameter hole portion 11. In addition, a hydraulic pressure supply hole 14 for supplying hydraulic pressure from the outside is provided in an inner surface of the intermediate hole portion 13.

[0015] In addition, as in the Fig. 1 and Fig. 2, the sleeve 4 in this embodiment includes circumferential grooves (recesses, grooves) 16 on the inner surface of the large-diameter hole portion 11. The circumferential grooves 16 are formed over the entire circumference, isolated from the intermediate hole portion 13, at two locations separated by a distance L1 and a distance L2 in the direction of the axis O from one end of the intermediate hole portion 13 on the large-diameter hole portion 11 side. Each of the circumferential grooves 16 has a groove width W and a depth G.

[0016] The circumferential grooves 16 can be arranged at any location. Furthermore, the number of circumferential grooves 16 can be one or three or more. The groove widths W and the depths G of the circumferential grooves 16 can be the same or different.

[0017] The volume V of each of the circumferential grooves 16 is determined as follows.

[0018] Specifically, the volume V of each of the circumferential grooves 16 is set to be larger than a volume obtained by multiplying a difference between the lateral cross-sectional area of ​​the large-diameter hole portion 11 and the lateral cross-sectional area of ​​the small-diameter hole portion 12, in other words, the lateral cross-sectional area of ​​the step 8, by the distance L1 from the intermediate hole portion 13 to the circumferential groove 16.

[0019] Specifically, the volume V of each of the circumferential grooves 16 is determined according to the following equation. V=((D1+G)2−D12)⋅πW / 4>(D12−D22)⋅πL1 / 4

[0020] The operation of the thus formed sleeve 4 and the rotor 1 according to this embodiment will be described below. To assemble the rotor 1 according to this embodiment, the iron core and the side ring 10 are previously shrink-fitted to the outer surface of the sleeve 4.

[0021] Then, the main shaft 2 is inserted into the through hole 3 of the sleeve 4 by shrinking from the left side to the right side in relation to the assembly of the sleeve 4, the iron core 9 and the side ring 10. Fig. 1. By abutting the stop surface 7 of the main shaft 2 against an end surface of the sleeve 4 on the large-diameter hole portion 11 side, the main shaft 2 and the sleeve 4 can be positioned in the direction along the axis O.

[0022] In this state, the small-diameter shaft portion 5 of the main shaft 2 is closely contacted with the small-diameter hole portion 12 of the sleeve 4, and the large-diameter shaft portion 6 of the main shaft 2 is closely contacted with the large-diameter hole portion 11 of the sleeve 4, and thus the main shaft 2 and the sleeve 4 are secured with respect to each other. This defines an airtight space between the main shaft 2 and the sleeve 4. The positional relationship between the sleeve 4 and the main shaft 2 at this time is referred to as the rotor position A.

[0023] At the rotor position A, a cylindrical first space (airtight chamber) S1 is defined between the intermediate hole portion 13 and an outer surface of the main shaft 2 facing the intermediate hole portion 13 in the radial direction. In addition, at the position of the large-diameter hole portion 11, two annular second spaces S2 and S3 are defined, respectively, between the circumferential groove 16 and the outer surface of the large-diameter shaft portion 6 of the main shaft 2 facing the circumferential grooves 16. In this state, the first space S1 and the second spaces S2 and S3 do not communicate with each other and serve as independent airtight spaces.

[0024] To disassemble the rotor 1 as shown in Fig. 3 at location A of the rotor, high-pressure hydraulic pressure is supplied to the first space S1 via the hydraulic pressure supply hole 14. Since the first space S1 and the second spaces S2 and S3 are not connected to each other, the hydraulic pressure is initially supplied only to the first space S1.

[0025] In the first space S1, a force acts due to the hydraulic pressure, which expands the sleeve 4 in the radial direction, as indicated by an arrow P1 in Fig. 3. In addition, an axial force proportional to the difference between the lateral cross-sectional areas of the large-diameter shaft section 6 and the small-diameter shaft section 5 acts on the step 8 provided in the main shaft 2, as indicated by an arrow P2.

[0026] As a result, the contact pressure between the small diameter shaft portion 5 and the small diameter hole portion 12 and the contact pressure between the large diameter shaft portion 6 and the large diameter hole portion 11 decreases, and the main shaft 2 can be easily removed from the sleeve 4 due to the axial force generated by the hydraulic pressure.

[0027] Specifically, when the axial force due to the hydraulic pressure exceeds the sum of the static friction forces proportional to the contact pressure between the small diameter shaft portion 5 and the small diameter hole portion 12 and the contact pressure between the large diameter shaft portion 6 and the large diameter hole portion 11, the removal of the main shaft 2 from the sleeve 4 begins.

[0028] It also illustrates Fig. 4, a rotor position B at which, during the process of removing the main shaft 2 from the sleeve 4, the boundary between the large-diameter shaft portion 6 and the small-diameter shaft portion 5 approaches one of the circumferential grooves 16. At this location B of the rotor, a new airtight chamber is formed in which the first space S1 and the second space S2 communicate with each other, and the hydraulic pressure in the first space S1 is also directed into the second space S2.

[0029] It also illustrates Fig. 5, a position C of the rotor, which is a state where the main shaft 2 is farther away from the sleeve 4. At this rotor position C, since the boundary between the large-diameter shaft portion 6 and the small-diameter shaft portion 5 approaches the other circumferential groove 16, the first space S1 and the two second spaces S2 and S3 communicate with each other, and the hydraulic pressure is also supplied to the second space S3. Fig. 6 shows a rotor position D, which is a state in which the fit between the large-diameter shaft portion 6 and the large-diameter hole portion 11 is completely loosened.

[0030] Fig. Figure 7 illustrates the changes in hydraulic pressure in the airtight chamber and the volume of the airtight chamber with respect to the rotor positions from the Fig. 3 shown rotor position A to the Fig. 6 shown rotor position D. According to Fig. 7, the hydraulic pressure in the airtight chamber increases when the supply of hydraulic pressure starts at the rotor position A, while the rotor position and the volume of the airtight chamber are maintained.

[0031] As the hydraulic pressure in the airtight chamber continues to increase, the main chamber 2 begins to move relative to the sleeve 4 in the axial direction O at the time when the axial force generated by the hydraulic pressure exceeds the static friction force. Accordingly, during the movement from the rotor position A to the rotor position B, the volume of the airtight chamber continuously increases by an amount equal to the value obtained by multiplying the lateral cross-sectional area of ​​the step 8 by the distance traveled. Therefore, the hydraulic pressure in the airtight chamber continuously decreases in conjunction with the increase in the volume of the airtight chamber.

[0032] Meanwhile, when the main shaft 2 moves with respect to the sleeve 4 in the direction along the axis O, the large-diameter shaft portion 6 is partially removed from the large-diameter hole portion 11, and the small-diameter shaft portion 5 is partially removed from the small-diameter hole portion 12; therefore, the contact area between the sleeve 4 and the main shaft 2 decreases. Accordingly, the frictional force between the sleeve 4 and the main shaft 2 decreases, and the distance of the main shaft 2 with respect to the sleeve 4 progresses.

[0033] Then, when the position of the main shaft 2 relative to the sleeve 4 reaches the rotor position B, the first space S1 communicates with the second space S2; therefore, the volume of the airtight chamber rapidly increases in a discontinuous manner, and the hydraulic pressure in the airtight chamber rapidly decreases. Accordingly, the axial force that removes the main shaft 2 from the sleeve 4 rapidly decreases, and the contact pressure between the sleeve 4 and the main shaft 2 increases; therefore, the movement of the main shaft 2 relative to the sleeve 4 is decelerated, and the main shaft 2 and the sleeve 4 stop relative to each other.

[0034] When the hydraulic pressure supplied to the airtight chamber is increased again in this state, the removal of the main shaft 2 from the sleeve 4 resumes at the time when the axial force due to the hydraulic pressure exceeds the static friction force between the sleeve 4 and the main shaft 2. Since the contact area between the sleeve 4 and the main shaft 2 is reduced, the removal continues in a state where the hydraulic pressure in the airtight chamber is lower than the hydraulic pressure at the rotor position A.

[0035] As in the situation described above, the volume of the airtight chamber continuously increases during the movement from the rotor position B to the rotor position C, and the hydraulic pressure in the airtight chamber continuously decreases. Meanwhile, the contact area between the sleeve 4 and the main shaft 2 decreases due to the movement of the main shaft 2 with respect to the sleeve 4 in the axial direction O, and due to the balance between the two, the distance of the main shaft 2 with respect to the sleeve 4 progresses.

[0036] Then, when the position of the main shaft 2 relative to the sleeve 4 reaches the rotor position C, the first space S1 communicates with the second spaces S2 and S3; therefore, the volume of the airtight chamber rapidly increases again in a discontinuous manner, and the hydraulic pressure in the airtight chamber rapidly decreases. Accordingly, the movement of the main shaft 2 relative to the sleeve 4 is decelerated, and the sleeve 4 and the main shaft 2 stop again relative to each other.

[0037] Also, in the case of movement from rotor position C toward rotor position D, as in the situation described above, removal is resumed by again increasing the hydraulic pressure supplied to the airtight chamber. Since the contact area between sleeve 4 and main shaft 2 is reduced, removal begins in a state where the hydraulic pressure in the airtight chamber is lower than the hydraulic pressure at rotor position B.

[0038] During the movement from the rotor position C to the rotor position D, the hydraulic pressure in the airtight chamber also continuously decreases, while the contact area between the sleeve 4 and the main shaft 2 decreases, and due to the balance between these two, the distance of the main shaft 2 with respect to the sleeve 4 increases.

[0039] Then, when the position of the main shaft 2 relative to the sleeve 4 reaches the rotor position D, the fit between the large-diameter shaft portion 6 and the large-diameter hole portion 11 and the fit between the small-diameter shaft portion 5 and the small-diameter hole portion 12 are completely loosened, and the airtight chamber is opened to the outside. Accordingly, the removal of the main shaft 2 from the sleeve 4 is completed.

[0040] Specifically, in the rotor 1 and the sleeve 4 according to this embodiment, instead of removing the main shaft 2 from the sleeve 4 all at once by means of the hydraulic pressure supplied to the airtight chamber, the removal is stopped at the locations of the two circumferential grooves 16. Furthermore, the hydraulic pressure for resuming the removal of the main shaft 2 from the sleeve 4 is kept sufficiently low compared to the initial hydraulic pressure; therefore, there is an advantage in that the main shaft 2 can be prevented from being quickly removed from the sleeve 4.

[0041] This is particularly effective in the case where the difference ΔD between the outer diameter dimensions (diameters) of the large-diameter shaft portion 6 and the small-diameter shaft portion 5 is small. Specifically, by suppressing the outer diameter of the main shaft 2, the outer diameter of the rotor 1 is suppressed, and thus, it is possible to prevent an increase in the size of the motor. Therefore, it is preferable that the outer diameter of the large-diameter shaft portion 6 be small.

[0042] On the other hand, in the case where a hollow hole is formed along the central axis of the main shaft 2, it is preferable to ensure that the inner diameter of the hollow hole is large. Accordingly, it is possible to insert a workpiece with a large outer diameter into the hollow hole. If the outer diameter of the small-diameter shaft portion 5 is small, the wall thickness of the small-diameter shaft portion 5 decreases, and thus the rigidity of the main shaft 2 also decreases. Therefore, it is preferable to make the outer diameter of the small-diameter shaft portion 5 large. In other words, it is preferable to make the difference ΔD between the outer diameter dimensions of the large-diameter shaft portion 6 and the small-diameter shaft portion 5 small.

[0043] In this case, with a small difference ΔD between the outer diameter dimensions, it is necessary to increase the hydraulic pressure to achieve an axial force that exceeds the static friction force. In a conventional method in which the main shaft 2 is removed from the sleeve 4 all at once, the main shaft 2 quickly pops out of the sleeve 4 due to the high hydraulic pressure applied to exceed the static friction force.

[0044] In contrast, in this embodiment, the removal of the main shaft 2 from the sleeve 4 is stopped at each circumferential groove 16, and the removal continues with a lower hydraulic pressure. Therefore, the removal of the main shaft 2 from the sleeve 4 is performed stepwise, and thus, it is possible to effectively prevent the main shaft 2 from jumping out of the sleeve 4 quickly.

[0045] It should be noted that in the rotor 1 of this embodiment, in addition to the circumferential grooves 16 provided in the large-diameter hole portion 11, circumferential grooves (recesses, grooves) 17 may be provided in the small-diameter shaft portion 5 at the locations where the small-diameter shaft portion 5 is fitted into the small-diameter hole portion 12, as shown in Fig. 8. In the Fig. 8, the circumferential grooves 17 are provided at positions separated in the axial direction O by the distances L3, L4 from the boundary between the intermediate hole portion 13 and the small diameter hole portion 12 at the rotor position A.

[0046] Accordingly, at the rotor position A, two annular third spaces S4 and S5 are defined, respectively, at the position of the small-diameter shaft portion 5 between the circumferential grooves 17 and the inner surface of the small-diameter hole portion 12 facing the circumferential groove 17. At the rotor position A, the first space S1 and the two third spaces S4 and S5 are not communicated with each other and serve as independent airtight spaces.

[0047] Accordingly, when removing the main shaft 2 from the sleeve 4, it is possible to increase the volume of the airtight chamber in a discontinuous manner at the time when the boundary between the intermediate hole portion 13 and the small diameter hole portion 12 approaches each of the circumferential grooves 17 of the small diameter shaft portion 5.

[0048] The number, groove widths and depths of the circumferential grooves 17 to be provided in the small diameter shaft section 5 can be determined arbitrarily.

[0049] Furthermore, the distances L1 to L4 can be adjusted such that the distances L3 = L1 and L4 = L2 at the rotor position B, the second space S2 and the third space S4 simultaneously communicate with the first space S1, and it is possible to quickly increase the volume of the airtight chamber. In particular, compared to the case where the circumferential grooves 16 are provided only in the large-diameter hole portion 11, it is possible to double the increase in the volume of the airtight chamber.

[0050] Alternatively, it is also possible to increase the volume of the airtight chamber by reducing the groove widths of the respective circumferential grooves 17 by an amount equivalent to that resulting when the circumferential grooves 16 are provided only in the large-diameter hole portion 11. By reducing the groove widths of the circumferential grooves 17, the sleeve 4 and the main chamber 2 can be more firmly attached to each other by increasing the contact area between the large-diameter hole portion 11 and the large-diameter shaft portion 6 and the contact area between the small-diameter hole portion 12 and the small-diameter shaft portion 5.

[0051] In addition, by adjusting the distances L1 to L4 such that the distances L3 and L1 and L4 and L2 are equal, it is possible to shift the timing at which the first space S1 communicates with the second space S2 and the third space S4. Accordingly, it is possible to increase the number of stops when removing the main shaft 2 from the sleeve 4.

[0052] Additionally, in this embodiment, the sleeve 4 and the main shaft 2 are stopped relative to each other at the time when the first space S1 communicates with the second spaces S2 and S3 or the third spaces S4 and S5. Alternatively, the sleeve 4 and the main shaft 2 can be decelerated without being stopped relative to each other by adjusting the dimensions of the recesses, such as the groove widths W and the depths G of the circumferential grooves 16, 17. In this way, a braking effect is also achieved when removing the main shaft 2 from the sleeve 4, whereby the main shaft 2 can be effectively prevented from quickly jumping out of the sleeve 4.

[0053] In addition, the Fig. 8 illustrates the case where the circumferential grooves 16, 17 are provided both in the large-diameter hole portion 11 of the sleeve 4 and in the small-diameter shaft portion 5 of the main shaft 2; alternatively, however, the circumferential grooves 17 may be provided only in the small-diameter shaft portion 5 of the main shaft 2.

[0054] Furthermore, in this embodiment, the case where the large-diameter shaft portion 6 and the small-diameter shaft portion 5 of the sleeve 4 have cylindrical inner surfaces has been described by way of example. Alternatively, as shown in Fig. 9, an interference in the radial direction between the large-diameter hole portion 11 and the large-diameter shaft portion 6 can be formed by a tapered inner surface which continuously decreases along the axial direction O in a direction from the small-diameter hole portion 12 to the large-diameter hole portion 11.

[0055] Furthermore, an interference between the small-diameter hole portion 12 and the small-diameter shaft portion 5 may be formed by a tapered inner surface that continuously decreases along the axial direction O in the direction from the small-diameter hole portion 12 to the large-diameter hole portion 11. Only the small-diameter hole portion 12 may have the tapered inner surface.

[0056] In addition, as in Fig. 10, the interference in the radial direction between the large-diameter hole portion 11 and the large-diameter shaft portion 6 can be formed by a shape whose size gradually decreases along the axial direction O in the direction from the small-diameter hole portion 12 to the large-diameter hole portion 11. In the Fig. In the example illustrated in FIG. 10, the large-diameter hole portion 11 is provided with a plurality of cylindrical inner surfaces with different inner diameters. Furthermore, the interference between the small-diameter hole portion 12 and the small-diameter shaft portion 5 may be formed by a shape that gradually decreases along the axial direction O in the direction from the small-diameter hole portion 12 to the large-diameter hole portion 11, or only the small-diameter hole portion 12 may have such a shape.

[0057] With the above-described configuration, when the main shaft 2 is removed from the sleeve 4, the interference in the portion where the large-diameter hole portion 11 and the large-diameter shaft portion 6 or the small-diameter hole portion 12 and the small-diameter shaft portion 5 fit together decreases. Therefore, as the removal of the main shaft 2 from the sleeve 4 progresses, the contact pressure between the sleeve 4 and the main shaft 2 decreases.

[0058] This has the advantage that the hydraulic pressure for resuming mining at rotor position B and rotor position C, as shown in Fig. 11 illustrates, in comparison to the Fig. 7 shown case (catenary line) can be further reduced.

[0059] Furthermore, in this embodiment, the circumferential grooves 16 are used as recesses to be provided in the large-diameter hole portion 11; however, this is not limited thereto. For example, instead of the circumferential grooves 16 extending over the entire circumference, grooves formed sectionally in a circumferential direction may be used, or, as shown in Fig. As illustrated in Figure 12, a plurality of arcuate grooves 18 may be provided with intervals therebetween in the circumferential direction. Furthermore, instead of grooves, the recesses may be, for example, holes of any shape.

[0060] Specifically, in this embodiment, it is sufficient for the inner surface of the through-hole 3 to have a shape that causes the volume of the airtight chamber to increase in a discontinuous manner before the connection between the through-hole 3 and the main shaft 2 is loosened due to the hydraulic pressure supplied to the airtight chamber. Accordingly, when the main shaft 2 is removed from the sleeve 4, a brake is applied, so that rapid pop-out of the main shaft 2 from the sleeve 4 can be effectively prevented.

[0061] As described above, in the sleeve 4 and the rotor 1 according to the present disclosure, when the main shaft 2 is removed from the sleeve 4, the removal is slowed down or stopped, so that rapid jumping out of the main shaft 2 from the sleeve 4 can be effectively prevented.

[0062] Although the embodiments of the present disclosure have been described in detail, the present disclosure is not limited to the individual embodiments described above. In the embodiments, various additions, replacements, changes, partial deletions, etc. are possible within the range that does not deviate from the scope of the disclosure, or within the range that does not deviate from the matters stated in the claims and the spirit and purpose of the present disclosure derived from their equivalents. For example, in the embodiments described above, the order of respective operations and the order of respective methods are given as examples and are not limited thereto. Furthermore, the same applies to cases where numerical values ​​or mathematical formulas are used in the description of the embodiments described above. {Reference symbol list} 1.20 rotor 2 Main shaft (shaft) 3 through holes 4 Sleeve (sleeve for one rotor) 5 Small diameter shaft section 6 Large diameter shaft section 11 Large diameter hole section 12 small diameter hole section 13 Intermediate hole section 14 Hydraulic pressure supply hole 16, 17 circumferential groove (recess, groove) 18 Groove (recess) O axis

Claims

[1] A sleeve for a rotor, the sleeve comprising a through hole for fitting a shaft having a small diameter shaft portion and a large diameter shaft portion which are different in outer diameter dimension and arranged side by side in an axial direction, wherein: the through hole comprises a small-diameter hole portion and a large-diameter hole portion which are arranged at positions spaced apart from each other in the axial direction and are respectively fitted into the small-diameter shaft portion and the large-diameter shaft portion in close contact, and an intermediate hole portion which forms an airtight chamber supplied with hydraulic pressure between the small-diameter hole portion and the large-diameter hole portion; and one or more recesses isolated from the intermediate hole portion are provided on an inner surface of the large diameter hole portion. [2] A sleeve for a rotor according to claim 1, wherein the recesses are grooves provided along a circumferential direction. [3] A sleeve for a rotor according to claim 1 or 2, wherein the volumes of the recesses are larger than a volume calculated by multiplying a difference between a lateral cross-sectional area of the large-diameter hole portion and a lateral cross-sectional area of the small-diameter hole portion by a distance of the intermediate hole portion to the recesses. [4] A sleeve for a rotor according to any one of claims 1 to 3, wherein the small diameter hole portion and the small diameter shaft portion and the large diameter hole portion and the large diameter shaft portion are each force-fitted into each other. [5] A sleeve for a rotor according to claim 4, wherein an interference in the radial direction between the small diameter hole portion and the small diameter shaft portion and / or an interference in the radial direction between the large diameter hole portion and the large diameter shaft portion decreases along the axial direction in a direction from the small diameter hole portion to the large diameter hole portion. [6] A sleeve for a rotor according to claim 5, wherein an inner surface of the small diameter hole portion and / or the inner surface of the large diameter hole portion has a tapered surface on which the interference changes continuously in the axial direction. [7] A sleeve for a rotor according to claim 5, wherein an inner surface of the small diameter hole portion and / or the inner surface of the large diameter hole portion has a shape in which the interference changes stepwise in the axial direction. [8] A sleeve for a rotor, the sleeve comprising a through hole for fitting a shaft having a small diameter shaft portion and a large diameter shaft portion which are different in outer diameter dimension and arranged side by side in an axial direction, wherein: the through hole comprises a small-diameter hole portion and a large-diameter hole portion which are arranged at positions spaced apart from each other in the axial direction and are fitted in close contact with the small-diameter shaft portion and the large-diameter shaft portion, respectively, and an intermediate hole portion which forms an airtight chamber supplied with hydraulic pressure between the small-diameter hole portion and the large-diameter hole portion; and an inner surface of the through-hole has a shape which causes a volume of the airtight chamber to increase in a discontinuous manner due to the hydraulic pressure supplied to the airtight chamber before the fitting between the through-hole and the shaft is loosened. [9] Rotor comprising: the sleeve for a rotor according to one of claims 1 to 8; and the shaft which is to be fitted into the through hole of the sleeve for a rotor. [10] Rotor comprising: a shaft comprising a small-diameter shaft portion and a large-diameter shaft portion which differ in outer diameter dimension and are arranged side by side in an axial direction; and a sleeve for a rotor, the sleeve having a through hole for fitting the shaft, wherein the through hole comprises a small-diameter hole portion and a large-diameter hole portion which are arranged at positions spaced apart from each other in the axial direction and are respectively fitted into the small-diameter shaft portion and the large-diameter shaft portion in close contact, and an intermediate hole portion which forms an airtight chamber supplied with hydraulic pressure between the small-diameter hole portion and the large-diameter hole portion; and one or more recesses isolated from the intermediate hole portion are provided on an outer surface of the small-diameter shaft portion at a position where the small-diameter shaft portion fits into the small-diameter hole portion.

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