JP4053563B2 - Fluid machinery - Google Patents

Description

  The present invention relates to a fluid machine, and more particularly to a fluid machine in which a shaft and an impeller are interconnected by an interference fit.

  In a high-speed rotating fluid machine such as a blower used in a laser oscillator, it is necessary to attach an impeller to a shaft (rotating shaft) with high accuracy and strength. Therefore, conventionally, as described in Patent Document 1, for example, the impeller is shrink-fitted on the shaft to prevent relative fluctuation in the circumferential direction that may occur during both high-speed rotations, and stable high-speed rotation is performed. I can do it. Further, as described in Patent Document 2, a configuration in which only a part of a shaft hole provided in an impeller is fitted to a shaft by shrink fitting is also known. In Patent Document 2, the impeller is further placed on the surface plate with the gas inlet side facing upward, and in that state, the fitting portion provided on the gas inlet side of the shaft hole of the impeller is heated to expand the diameter, A method is described in which when the shaft is inserted from above the impeller into the shaft hole to a predetermined position, the heating is canceled and the shrink fitting is completed.

JP-A-7-63193 (FIG. 2) JP 2004-60460 A (FIGS. 1 and 2)

  In a conventional fluid machine in which the impeller is shrink-fitted onto the shaft, generally, the position where the impeller and the shaft first engage with each other when the impeller contracts is determined as a reference, and then the impeller is fixed. Is completely contracted and firmly fixed to the shaft. At this time, it is generally difficult to accurately predict the fixing position of the impeller on the shaft (that is, the position of the first engagement portion) due to variations in processing accuracy. Therefore, it becomes difficult to accurately position and fix the impeller at a predetermined axial position on the shaft, and as a result, there is a concern that the operation reliability and performance of the fluid machine may be adversely affected.

  For example, in a configuration in which a shaft seal or bearing is installed adjacent to the impeller, if the axial position of the impeller on the shaft deviates from the set position, the axial position of the shaft seal or bearing is also affected by the influence. It will deviate from. In particular, when a positional shift occurs in the bearing, abnormal vibration may occur during high-speed rotation of the shaft, which may cause damage to the bearing and the fluid machine body. Such a problem is not only the configuration in which the impeller is fixed to the shaft with the whole shaft hole as described in Patent Document 1 described above, but also the impeller as described in Patent Document 2 described above. Even in a configuration in which a part of the shaft is fixed to the shaft, the same may occur because it is difficult to specify the fixing position of the impeller on the shaft (that is, the position of the first engagement portion).

  In order to solve such a problem, in the shrink fitting process, the impeller and the shaft are held by a press machine or the like until the impeller is completely contracted, thereby the relative position in the axial direction between the two. Measures to prevent deviation may be taken. In addition, a dedicated cooling mechanism may be prepared for the purpose of shortening the time until the impeller contraction is completed. However, such incidental equipment such as a press machine and a cooling mechanism can increase the manufacturing cost of the fluid machine.

  An object of the present invention is to ensure relative displacement in the axial direction between a shaft and an impeller in a fluid machine in which the shaft and the impeller are mutually coupled by an interference fit, with a simple configuration. An object of the present invention is to provide a low-cost and high-performance fluid machine that can be prevented and that is excellent in safety and operational reliability.

To achieve the above object, the invention described in claim 1 comprises a shaft and an impeller having a shaft hole into which the shaft is inserted, and the impeller is coupled to the shaft by an interference fit as a result of thermal deformation. In a fluid machine, a positioning portion that is provided between a shaft and an impeller, positions the impeller at a predetermined position of the shaft, and is provided in a shaft hole adjacent to the positioning portion. A fitting portion that forms an interference fit between the fitting portion and a loose insertion portion that is provided in the shaft hole adjacent to the fitting portion and forms a gap between the shaft and the impeller. A fluid machine is provided.

  The invention according to claim 2 provides the fluid machine according to claim 1, wherein the positioning portion includes a member separate from the shaft and the impeller.

  According to a third aspect of the present invention, there is provided the fluid machine according to the first or second aspect, wherein the positioning portion includes a part of at least one of a shaft and an impeller.

  The invention according to claim 4 is the fluid machine according to any one of claims 1 to 3, wherein the fitting portion and the loose insertion portion are at least one of an outer diameter of the shaft and an inner diameter of the shaft hole of the impeller. Is provided along the axial direction.

  According to the first aspect of the present invention, when the shaft is fixed to the impeller by at least one of shrink fitting and cold fitting, the fitting portion is provided in the shaft hole of the impeller adjacent to the positioning portion. Thus, it is possible to easily and surely specify the fixing position of the impeller on the shaft (that is, the position of the first engagement portion) and achieve the interference fit in the fitting portion. Then, by providing the loose insertion portion adjacent to the fitting portion in the shaft hole, the expansion direction of the shaft and the contraction direction of the impeller after the interference fit in the fitting portion can be controlled to a prescribed direction. As a result, the relative positional shift in the axial direction between the shaft and the impeller when mutually coupled is reliably prevented with a simple configuration, and the axial positional accuracy of the impeller on the shaft is improved. The axial position accuracy of other parts attached to the shaft adjacent to the impeller can also be improved. Therefore, an inexpensive and high-performance fluid machine excellent in safety and operational reliability is provided.

  According to the second aspect of the present invention, since the positioning part can be configured by using other parts attached to the shaft adjacent to the impeller, the number of processing steps and the number of parts can be reduced.

  According to invention of Claim 3, the stable positioning function by a positioning part can be maintained.

  According to invention of Claim 4, a fitting part and a loose insertion part can be comprised very simply.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.
Referring to the drawings, FIG. 1 shows a shaft 12 and an impeller 14 of a fluid machine 10 according to one embodiment of the present invention. The fluid machine 10 according to the illustrated embodiment has a configuration of a centrifugal blower, and since the blade structure of the impeller 14 and the structure of the housing (not shown) can both be known, the description thereof is omitted. . The present invention can be applied not only to the centrifugal blower but also to various other fluid machines.

  The fluid machine 10 includes a shaft 12 and an impeller 14 having a shaft hole 16 into which the shaft 12 is inserted, and the impeller 14 is coupled to the shaft 12 by an interference fit. The fluid machine 10 is further provided between the shaft 12 and the impeller 14, a positioning portion 18 that positions the impeller 14 at a predetermined position of the shaft 12, and a shaft hole 16 adjacent to the positioning portion 18. A fitting portion 20 that forms an interference fit between the shaft 12 and the impeller 14 and a shaft hole 16 adjacent to the fitting portion 20, and a gap between the shaft 12 and the impeller 14. The loose insertion part 22 which forms is provided.

  The shaft 12 has a stepped cylindrical outer peripheral surface 12a extending in a stepwise manner along the rotational axis A of the shaft 12 and the impeller 14, and the impeller 14 is concentrically arranged at a predetermined position in the axial direction. Fixed. The shaft hole 16 of the impeller 14 has a cylindrical inner peripheral surface 16 a that extends with the same inner diameter along the rotational axis A of the shaft 12 and the impeller 14. The shaft 12 to which the impeller 14 is fixed is rotatably supported by a housing (not shown) via a bearing 24 attached at a predetermined position in the axial direction. A shaft seal 26 is fixedly installed at a predetermined position in the axial direction of the shaft 12 between the impeller 14 and the bearing 24.

  The outer peripheral surface 12a of the shaft 12 is a cylindrical large-diameter portion 28 on which the bearing 24 and the shaft seal 26 are installed, and is disposed adjacent to the large-diameter portion 28 in the axial direction and is substantially perpendicular to the rotation axis A. A cylindrical middle diameter portion 30 slightly reduced in diameter via the annular shoulder surface 12b, and a second annular shoulder surface 12c disposed adjacent to the middle diameter portion 30 in the axial direction and substantially perpendicular to the rotation axis A. And a small cylindrical portion 32 having a slightly reduced diameter. The shaft seal 26 has a cylindrical base portion 34 that fits into the large-diameter portion 28 of the shaft 12, and the base portion 34 is at one end in the axial direction (upper end in the figure) on the first annular shoulder surface 12 b of the shaft 12. It arrange | positions in alignment and is arrange | positioned adjacent to the bearing 24 in the axial direction other end (lower end in a figure). The impeller 14 is fixed to the medium-diameter portion 30 of the shaft 12 in a first region 36 extending from a first axial end (lower end in the drawing) to a predetermined length of the inner peripheral surface 16 a of the shaft hole 16. The remaining region (second region) 38 of the inner peripheral surface 16 a of the shaft hole of the impeller 14 is disposed in a non-contact manner with the small diameter portion 32 of the shaft 12.

  In the illustrated embodiment, the positioning portion 18 includes a first annular shoulder surface 12 b of the shaft 12 and a base portion 34 of a shaft seal 26 that is a separate member from the shaft 12 and the impeller 14. The impeller 14 sequentially receives the small-diameter portion 32 and the medium-diameter portion 30 of the shaft 12 from one axial end (the lower end in the drawing) of the shaft hole 16, and is adjacent to the opening at one axial end of the shaft hole 16. In the annular region 14a, the first annular shoulder surface 12b of the shaft 12 is brought into contact with one axial end surface (upper end surface in the drawing) of the base portion 34 of the shaft seal 26. In this state, the impeller 14 is accurately positioned at a predetermined position in the axial direction on the shaft 12.

  In the illustrated embodiment, the fitting portion 20 is configured by the cooperation of the medium diameter portion 30 of the outer peripheral surface 12 a of the shaft 12 and the first region 36 of the inner peripheral surface 16 a of the shaft hole 16. The interference fit structure in the fitting portion 20 is at least one of “shrink fit” in which the impeller 14 is heated and attached to the shaft 12 and “cooled fit” in which the shaft 12 is cooled and attached to the impeller 14. (That is, including the combined use). The outer diameter of the medium-diameter portion 30 of the shaft 12 and the inner diameter of the first region 36 of the shaft hole 16 are set so as to ensure a sufficient allowance for achieving an interference fit structure with a desired strength. The axial dimension of the medium diameter portion 30 of the shaft 12 is set to a size sufficient to eliminate the inclination of the axis of the impeller 14 with respect to the shaft 12. Further, in the illustrated embodiment, the loose insertion portion 22 is configured by the cooperation of the small diameter portion 32 of the outer peripheral surface 12 a of the shaft 12 and the second region 38 of the inner peripheral surface 16 a of the shaft hole 16.

  In the fluid machine 10 having the above-described configuration, when the shaft 12 is fixed to the impeller 14 by at least one of shrink fitting and cold fitting, first, the small diameter portion 32 and the medium diameter portion 30 of the shaft 12 are sequentially moved to the impeller. 14 is inserted into the shaft hole 16 and the annular region 14a on the end surface in the axial direction of the impeller 14 is brought into contact with the positioning portion 18 (the first annular shoulder surface 12b of the shaft 12 and the base portion 34 of the shaft seal 26). 14 can be accurately positioned at a predetermined position in the axial direction on the shaft 12. If left in that state, the heated impeller 14 contracts in the case of shrink fitting, and the cooled shaft 12 expands in the case of cold fitting, and the fitting portion 20 (the inner diameter portion of the shaft 12). 30 and the first region 36) of the shaft hole 16) the shaft 12 and the impeller 14 are initially engaged. At this time, the state in which the annular region 14a of the impeller 14 abuts against the positioning portion 18 can be easily maintained by the weight of the impeller 14 or a slight external force, so that the impeller 14 is placed at a predetermined axial position on the shaft 12. In the positioned state, the shaft 12 and the impeller 14 are first engaged at an arbitrary position of the fitting portion 20.

  Subsequently, the shaft 12 and the impeller 14 in contact with each other exchange heat, so that the expansion of the shaft 12 and the contraction of the impeller 14 proceed substantially simultaneously, and the interference fit in the fitting portion 20 is completed. The subsequent expansion of the shaft 12 and the contraction of the impeller 14 proceed in opposite directions as indicated by arrows in FIG. 1, and the thermal deformation of both in the opposite direction is caused by the loose insertion portion 22 (shaft This is performed smoothly due to the presence of the 12 small diameter portions 32 and the second region 38 of the shaft hole 16. Then, when the thermal deformation of both the shaft 12 and the impeller 14 is completed, the mounting operation of the impeller 14 to the shaft 12 is completed. Thus, the impeller 14 attached to the shaft 12 has extremely high positional accuracy in the axial direction.

  As described above, in the fluid machine 10, when the shaft 12 is fixed to the impeller 14 by at least one of shrink fitting and cooling fitting, the fitting portion 20 is placed in the shaft hole 16 adjacent to the positioning portion 18. By providing the above, it is possible to easily and surely specify the fixing position of the impeller 14 on the shaft 12 (that is, the position of the first engagement portion) and achieve the interference fit in the fitting portion 20. Then, by providing the loose insertion portion 22 adjacent to the fitting portion 20 in the shaft hole 16, the expansion direction of the shaft 12 and the contraction direction of the impeller 14 after the interference fit can be controlled to a prescribed direction. it can. As a result, the relative positional displacement between the shaft 12 and the impeller 14 in the axial direction when the shaft 12 and the impeller 14 are mutually coupled can be reliably prevented with a simple configuration, and the axial position accuracy of the impeller 14 on the shaft 12 can be improved. In addition to the improvement, the axial position accuracy of other components such as the bearing 24 and the shaft seal 26 attached to the shaft 12 can also be improved. Therefore, the fluid machine 10 is inexpensive and has high performance with excellent safety and operational reliability.

  In the above-described configuration in which the interference fit between the shaft 12 and the impeller 14 is ensured by at least one of shrink fitting and cold fitting, the shaft 12 and the impeller 14 are made of materials having different thermal shrinkage rates. This is advantageous in terms of promoting an interference fit effect.

  In the fluid machine 10 described above, the positioning portion 18 includes the base portion 34 of the shaft seal 26 (that is, a member separate from the shaft 12 and the impeller 14) and the first annular shoulder surface 12b of the shaft 12 (that is, a part of the shaft 12). It is also possible to configure with only one of these. If the positioning part 18 is configured by diverting other parts such as the shaft seal 26 attached to the shaft 12 adjacent to the impeller 14, the number of processing steps and the number of parts can be reduced. On the other hand, if the positioning part 18 is comprised by at least one part of the shaft 12 and the impeller 14, the stable positioning function can be maintained.

  Moreover, the fitting part 20 and the loose insertion part 22 change at least one of the radial dimension of the outer peripheral surface 12a of the shaft 12 and the radial dimension of the inner peripheral surface 16a of the shaft hole 16 of the impeller 14 along the axial direction. Can be formed. According to such a structure, the fitting part 20 and the loose insertion part 22 can be comprised very simply. Hereinafter, various modified examples of the fluid machine 10 will be described with reference to FIGS. 2 to 5, components corresponding to the fluid machine 10 of FIG. 1 are denoted by common reference numerals, and redundant description is omitted.

  In the modification shown in FIG. 2, a tapered portion 40 that gradually reduces the outer diameter dimension from the first annular shoulder surface 12 b to the small diameter portion 32 is provided on the outer peripheral surface 12 a of the shaft 12 instead of the above-described medium diameter portion 30. Provided. The tapered portion 40 is a portion that is adjacent to the first annular shoulder surface 12b and is an interference fit state with the end portion 36a of the first region 36 adjacent to the opening end of the shaft hole 16 of the impeller 14 adjacent to the positioning portion 18 side. Are engaged to form the fitting portion 20. In this configuration, it is possible to achieve the required strength of fitting by sufficiently securing the interference of the interference fit in the fitting portion 20, and the positioning portion 18 (the first annular shoulder surface 12b of the shaft 12 and the shaft seal 26). The inclination of the axis of the impeller 14 with respect to the shaft 12 can be eliminated by the action of the base 34). Even with such a configuration, the same effects as the fluid machine 10 shown in FIG. 1 can be obtained.

  In the modification shown in FIG. 3, the medium diameter portion 30 and the second annular shoulder surface 12c described above are omitted from the outer peripheral surface 12a of the shaft 12, and the large diameter portion 28 and the small diameter portion 32 are replaced by the first annular shoulder surface 12b. The inner peripheral surface 16a of the shaft hole 16 of the impeller 14 is composed of the first region 36 that is a small-diameter cylindrical surface and a cylindrical surface that is larger in diameter than the first region 36. It is formed in a stepped cylindrical shape including the second region 38 described above. The first region 36 of the shaft hole 16 of the impeller 14 is engaged with the proximal end region 42 of the small-diameter portion 32 of the shaft 12 adjacent to the first annular shoulder surface 12b in a tight-fitting state, and the fitting portion 20 is engaged. Constitute. In this configuration, it is possible to achieve the required strength of fitting by sufficiently securing the interference of the interference fit in the fitting portion 20 and the axial length, and to eliminate the inclination of the axis of the impeller 14 with respect to the shaft 12. . Even with such a configuration, the same effects as the fluid machine 10 shown in FIG. 1 can be obtained.

  In the modification shown in FIG. 4, the outer peripheral surface 12a of the shaft 12 is shaped so that the large-diameter portion 28 and the small-diameter portion 32 are adjacent to each other via the first annular shoulder surface 12b, as in the configuration of FIG. 14 on the inner peripheral surface 16a of the fourteen shaft holes 16, and a tapered region for gradually reducing the inner diameter between the second region 38 having a large diameter cylindrical surface and the second region 38 to the opening end on the positioning portion 18 side. 44. The tapered region 44 of the shaft hole 16 is a portion adjacent to the opening end on the positioning portion 18 side, and is engaged with the end portion 32a of the small diameter portion 32 of the shaft 12 adjacent to the first annular shoulder surface 12b in an interference fit state. And the fitting part 20 is comprised. In this configuration, it is possible to achieve the required strength of fitting by sufficiently securing the interference of the interference fit in the fitting portion 20, and the positioning portion 18 (the first annular shoulder surface 12b of the shaft 12 and the shaft seal 26). The inclination of the axis of the impeller 14 with respect to the shaft 12 can be eliminated by the action of the base 34). Even with such a configuration, the same effects as the fluid machine 10 shown in FIG. 1 can be obtained.

  In the modification shown in FIG. 5, a positioning portion 46 composed of a part of both the shaft 12 and the impeller 14 is employed in the shaft hole 16 of the impeller 14 instead of the positioning portion 18 described above that also uses the shaft seal 26. ing. Specifically, the outer peripheral surface 12a of the shaft 12 is shaped so that the large-diameter portion 28 and the small-diameter portion 32 are adjacent to each other via the first annular shoulder surface 12b, and the large-diameter portion 28 is made the base 34 of the shaft seal 26. It extends so as to project from the shaft hole 16 and is inserted into the shaft hole 16 of the impeller 14. On the other hand, the inner peripheral surface 16a of the shaft hole 16 of the impeller 14 has a large-diameter first region 36 adjacent to the opening end on the shaft seal 26 side, and a large-diameter second region 38 adjacent to the opening end on the opposite side. The third region 48 having a small diameter located between the first region 36 and the second region 38 is formed in a stepped cylindrical shape. Between the first region 36 and the third region 48 of the shaft hole 16 of the impeller 14, an annular shoulder surface 16b substantially orthogonal to the axis A is formed. The annular shoulder surface 16 b of the shaft hole 16 of the impeller 14 constitutes a positioning portion 46 in cooperation with the first annular shoulder surface 12 b of the shaft 12. Further, the third region 48 of the shaft hole 16 of the impeller 14 is engaged with the proximal end region 50 of the small diameter portion 32 of the shaft 12 adjacent to the first annular shoulder surface 12b in an interference fit state. 20 is configured.

  In the above configuration, when the shaft 12 is fixed to the impeller 14 by at least one method of shrink fitting and cold fitting, first, the small diameter portion 32 and the large diameter portion 28 of the shaft 12 are sequentially arranged in the shaft hole 16 of the impeller 14. And the first annular shoulder surface 12b of the shaft 12 and the annular shoulder surface 16b of the shaft hole 16 of the impeller 14 are brought into contact with each other, whereby the impeller 14 is moved to the axial line on the shaft 12 by the action of the positioning portion 46. The direction can be accurately positioned at a predetermined position. In this state, the interference fit is completed in the fitting portion 20 (the base region 50 of the small diameter portion 32 of the shaft 12 and the third region 48 of the shaft hole 16), whereby the impeller 14 is moved in the axial direction on the shaft 12. It can be attached to the shaft 12 in a state of being accurately positioned at a predetermined position. In addition, during the heat exchange between the shaft 12 and the impeller 14 that are in mutual contact with each other in the fitting portion 20, the thermal deformation of both proceeds in the direction indicated by the arrow in FIG. Also in this configuration, the positioning portion 46 and the fitting portion 20 are provided adjacent to each other in the shaft hole 16, so that the fixing position of the impeller 14 on the shaft 12 (that is, the position of the first engagement portion) is determined. The interference fit at the fitting portion 20 can be achieved with ease and certainty. As a result, the same effects as the fluid machine 10 shown in FIG.

It is sectional drawing which shows the shaft and impeller of the fluid machine by one Embodiment of this invention. It is sectional drawing which shows the modification of the fluid machine of FIG. It is sectional drawing which shows the other modification of the fluid machine of FIG. It is sectional drawing which shows the further another modification of the fluid machine of FIG. It is sectional drawing which shows the further another modification of the fluid machine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fluid machine 12 Shaft 12a Outer peripheral surface 12b 1st cyclic | annular shoulder surface 12c 2nd cyclic | annular shoulder surface 14 Impeller 16 Shaft hole 16a Inner peripheral surface 18, 46 Positioning part 20 Fitting part 22 Free insertion part 24 Bearing 26 Shaft seal 28 Large diameter Portion 30 Medium diameter portion 32 Small diameter portion 34 Base portion 36 First region 38 Second region 40 Tapered portion 42, 50 Base end region 44 Tapered region 48 Third region

Claims (4)

In a fluid machine comprising a shaft and an impeller having a shaft hole into which the shaft is inserted, wherein the impeller is coupled to the shaft by an interference fit as a result of thermal deformation ;
A positioning portion that is provided between the shaft and the impeller and positions the impeller at a predetermined position of the shaft;
A fitting portion provided in the shaft hole adjacent to the positioning portion, and forming the interference fit between the shaft and the impeller;
A loose insertion portion that is provided in the shaft hole adjacent to the fitting portion and forms a gap between the shaft and the impeller;
A fluid machine comprising:   The fluid machine according to claim 1, wherein the positioning portion includes a member separate from the shaft and the impeller.   The fluid machine according to claim 1, wherein the positioning portion includes a part of at least one of the shaft and the impeller.   The fitting portion and the loose insertion portion are formed by changing at least one of an outer diameter of the shaft and an inner diameter of the shaft hole of the impeller along an axial direction. The fluid machine according to any one of the above.

Images