JP2022041042A - Centrifugal compressor - Google Patents

Abstract

To provide a centrifugal compressor capable of suppressing the operation of excessive fastening force on an impeller.SOLUTION: The centrifugal compressor includes a rotary shaft 310, and an impeller 100. The impeller 100 has: a hub 110 having an outer peripheral face 112, a back face 114, and a counterbore part 116; a plurality of blades 120; and a lid 130 fixed to the hub 110 to close the counterbore part 116. The hub 110 is formed with a through-hole 110h leading from the back face 114 to the counterbore part 116.SELECTED DRAWING: Figure 2

Description

The present invention relates to a centrifugal compressor.

For example, Japanese Patent Application Laid-Open No. 2017-180268 discloses a centrifugal compressor including an impeller and a rotating shaft connected to the impeller. The tip of the rotating shaft protrudes toward the suction side of the impeller, and a nut is connected to this tip.

Japanese Unexamined Patent Publication No. 2017-180268

When a centrifugal compressor as described in JP-A-2017-180268 is driven, the temperature on the discharge side of the impeller becomes higher than the temperature on the suction side of the impeller. Then, since the temperature of the rotating shaft and the bolt becomes lower than the temperature of the impeller, there is a concern that an excessive tightening force may be generated on the impeller depending on the respective thermal expansion coefficients of the rotating shaft, the nut, and the impeller.

An object of the present invention is to provide a centrifugal compressor capable of suppressing an excessive tightening force from acting on an impeller.

A centrifugal compressor according to one aspect of the present invention is a centrifugal compressor including a rotating shaft and an impeller fixed to the rotating shaft with a nut and rotating integrally with the rotating shaft. An outer peripheral surface having a shape that gradually increases in diameter from one side of the rotating shaft toward the other side, a back surface formed on the other side, a tip portion of the rotating shaft, and a counterbore portion accommodating the nut. The hub has a plurality of blades provided on the outer peripheral surface of the hub, and a lid fixed to the hub so as to close the counterbore portion. A through hole leading to the counterbore is formed.

According to the present invention, it is possible to provide a centrifugal compressor capable of suppressing an excessive tightening force from acting on the impeller.

It is a figure which shows schematic structure of the centrifugal compressor of one Embodiment of this invention. It is sectional drawing of an impeller. It is sectional drawing which shows the modification of the impeller.

Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are assigned the same number.

FIG. 1 is a diagram schematically showing a configuration of a centrifugal compressor according to an embodiment of the present invention. As shown in FIG. 1, the centrifugal compressor 1 includes an impeller 100, a turbine wheel 200, a rotary shaft 310, a nut 315, a motor 320, a bearing 330, and a casing 400.

The rotary shaft 310 connects the impeller 100 and the turbine wheel 200. The rotary shaft 310 is rotationally driven by the motor 320. The rotating shaft 310 is received by a bearing 330. The motor 320 has a rotor and a stator (not shown).

The casing 400 houses the impeller 100, the turbine wheel 200, the rotary shaft 310, the motor 320 and the bearing 330. The casing 400 has a compressor housing 410, a turbine housing 420, and a center housing 430.

The compressor housing 410 houses the impeller 100. The compressor housing 410 has a suction port 411 and a discharge portion 412. A diffuser (not shown) is provided on the discharge side of the impeller 100 in the compressor housing 410.

The turbine housing 420 houses the turbine wheel 200. The turbine housing 420 has a suction portion 421 and an discharge port 422.

The center housing 430 is arranged between the compressor housing 410 and the turbine housing 420. The center housing 430 houses the motor 320 and the bearing 330.

The center housing 430 has a rear housing 440. The rear housing 440 is provided between the impeller 100 and the bearing 330. As shown in FIG. 2, the rear housing 440 has a facing surface 442 facing the impeller 100. The facing surface 442 is formed flat.

The impeller 100 discharges the gas (for example, air) sucked from the suction port 411 from the discharge unit 412. As shown in FIG. 2, the impeller 100 includes a hub 110, a plurality of blades 120, and a lid 130. The impeller 100 is fixed to the rotating shaft 310 with a nut 315. The impeller 100 rotates integrally with the rotating shaft 310.

The hub 110 is rotatable around a rotation shaft 310. The hub 110 has an outer peripheral surface 112, a back surface 114, and a counterbore portion 116.

The outer peripheral surface 112 includes a portion having a shape that gradually increases in diameter from one side (upper side in FIG. 2) to the other side (lower side in FIG. 2) in the axial direction of the rotating shaft 310. In other words, the outer peripheral surface 112 includes a portion having a shape in which the outer diameter of the outer peripheral surface 112 gradually increases from the end portion on the suction side to the end portion on the discharge side. The portion has a shape curved so as to be convex in a direction approaching the axis A of the rotating shaft 310 from one side toward the other side.

The back surface 114 is orthogonal to the rotation axis 310. The back surface 114 is formed on the other side (discharge side). The back surface 114 is formed flat.

The counterbore portion 116 has a shape that is recessed from one side (suction side) of the hub 110 toward the back surface 114. The counterbore portion 116 accommodates the tip end portion of the rotating shaft 310. A nut 315 is connected to the tip of the rotating shaft 310. Therefore, the tip portion of the rotating shaft 310 and the nut 315 are housed in the counterbore portion 116. The counterbore portion 116 has a bottom surface 116a and an inner peripheral surface 116b.

The bottom surface 116a is formed flat. The bottom surface 116a is formed in a circular shape. The bottom surface 116a is orthogonal to the rotation axis 310.

The inner peripheral surface 116b is formed in a cylindrical shape. The inner peripheral surface 116b has a shape that rises from the edge of the bottom surface 116a in a direction parallel to the axis A. A recess 116b1 is formed on the inner peripheral surface 116b.

As shown in FIG. 2, the hub 110 is formed with a through hole 110h leading from the back surface 114 to the counterbore portion 116. The through hole 110h communicates the counterbore portion 116 and the portion outside the portion of the back surface 114 that overlaps in the axial direction with the counterbore portion 116. The opening end of the through hole 110h on the counterbore portion 116 side is formed on the inner peripheral surface 116b.

Each blade 120 is provided on the outer peripheral surface 112 of the hub 110. Each blade 120 has a shape extending from the vicinity of the one-sided end of the outer peripheral surface 112 to the other-side end. Each blade 120 is tilted in the direction of rotation of the hub 110.

The lid 130 is fixed to the hub 110 so as to close the counterbore portion 116. More specifically, the lid 130 has an inner circumference of the counterbore 116 so that the tip of the rotating shaft 310 and the nut 315 are located in the space S (see FIG. 2) formed by the lid 130 and the counterbore 116. It is press-fitted into the recess 116b1 of the surface 116b. The lid 130 is formed in a disk shape. The lid 130 thermally shields the space S from the suction side of the impeller 100. The lid 130 is preferably made of a heat insulating material. Alternatively, it is preferable that a heat insulating member is provided on at least one of the inner surface and the outer surface of the lid 130.

As shown in FIG. 2, the lid 130 is formed with an opening 130h penetrating the lid 130. The opening 130h is formed in a portion of the lid 130 including the shaft core A. The area of the opening 130h is smaller than the area (total area) of the through hole 110h. As a result, the pressure in the space S is reduced, so that the thrust load F (the load indicated by the arrow in FIG. 2) acting on the impeller 100 is reduced.

As described above, in the impeller 100 of the centrifugal compressor 1 of the present embodiment, the counterbore portion 116 is closed by the lid 130, and the back surface 114 of the hub 110 and the counterbore portion 116 communicate with each other through the through hole 110h. Therefore, the temperature of the space S formed by the counterbore portion 116 and the lid 130 is the temperature of the other side (discharge side) of the hub 110, which is higher than the temperature of one side (suction side) of the hub 110. That is, the temperature is substantially the same as the temperature on the back surface 114 side of the hub 110. Therefore, the temperature difference between the rotating shaft 310 and the nut 315 located in the counterbore portion 116 and the impeller 100 becomes small. Therefore, excessive tightening of the impeller 100 due to the difference in the coefficient of thermal expansion of the rotating shaft 310, the nut 315, and the impeller 100 is suppressed.

Further, since the lid 130 is press-fitted into the recess 116b1 of the counterbore portion 116, the lid 130 is suppressed from being detached from the hub 110.

It should be noted that the embodiments disclosed this time are examples in all respects and should be considered not to be restrictive. The scope of the present invention is shown by the scope of claims rather than the description of the embodiment described above, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

For example, as shown in FIG. 3, the through hole 110h may communicate the counterbore portion 116 of the back surface 114 and the portion of the back surface 114 that overlaps in the axial direction with the counterbore portion 116.

Further, as long as the area of the opening 130h is smaller than the area of the through hole 110h, the position, orientation, and number of the openings 130h are not limited to the above example.

[Aspect]
It will be understood by those skilled in the art that the above-mentioned exemplary embodiments are specific examples of the following embodiments.

A centrifugal compressor according to one aspect of the present disclosure is a centrifugal compressor including a rotating shaft and an impeller fixed to the rotating shaft with a nut and rotating integrally with the rotating shaft. An outer peripheral surface having a shape that gradually increases in diameter from one side of the rotating shaft toward the other side, a back surface formed on the other side, a tip portion of the rotating shaft, and a counterbore portion accommodating the nut. The hub has a plurality of blades provided on the outer peripheral surface of the hub, and a lid fixed to the hub so as to close the counterbore portion. A through hole leading to the counterbore is formed.

In the impeller of this centrifugal compressor, the counterbore portion is closed with a lid, and the back surface of the hub and the counterbore portion communicate with each other through the through hole, so that the temperature of the space formed by the counterbore portion and the lid is high. , The temperature on the other side (discharge side) of the hub, which is higher than the temperature on one side (suction side) of the hub, that is, the temperature on the back side of the hub is substantially the same. Therefore, the temperature difference between the rotating shaft and nut located in the counterbore portion and the impeller becomes small. Therefore, excessive tightening of the impeller due to the difference in the coefficient of thermal expansion of the rotating shaft, the nut, and the impeller is suppressed.

Further, it is preferable that the lid is formed with an opening penetrating the lid.

By doing so, the pressure in the space is reduced, so that the thrust load acting on the impeller is reduced.

Further, the area of the opening is preferably smaller than the area of the through hole.

By doing so, it is possible to suppress the formation of a flow from the discharge side of the impeller (the back surface side of the hub) toward the suction side of the impeller through the through hole and the opening.

For example, the through hole may communicate with a portion of the back surface outside the portion of the back surface where the counterbore portion and the portion of the rotation axis overlap in the axial direction and the counterbore portion.

On the back side of the hub, the pressure and temperature of the fluid gradually increase as the distance from the rotating shaft along the radial direction of the hub increases. Therefore, in this embodiment, the temperature of the rotating shaft and the nut and the impeller located in the counterbore portion. The difference is smaller.

Alternatively, the through hole may communicate the counterbore portion, the portion of the back surface that overlaps the counterbore portion in the axial direction, and the counterbore portion.

1 Centrifugal compressor, 100 impeller, 110 hub, 110h through hole, 112 outer peripheral surface, 114 back surface, 116 counterbore, 116a bottom surface, 116b inner peripheral surface, 116b1 recess, 120 blade, 130 lid, 130h opening, 200 turbine wheel, 310 rotating shafts, 315 nuts, 320 motors, 330 bearings, 400 casings, 410 compressor housings, 420 turbine housings, 430 center housings, 440 rear housings, 442 facing surfaces, A-axis cores.

Claims (5)

The axis of rotation and
A centrifugal compressor including an impeller fixed to the rotating shaft with a nut and rotating integrally with the rotating shaft.
The impeller is
An outer peripheral surface having a shape that gradually increases in diameter from one side of the rotating shaft to the other side, a back surface formed on the other side, a tip portion of the rotating shaft, and a counterbore portion accommodating the nut. With a hub that has
A plurality of blades provided on the outer peripheral surface of the hub,
It has a lid fixed to the hub so as to close the counterbore.
A centrifugal compressor in which a through hole leading from the back surface to the counterbore portion is formed in the hub. The centrifugal compressor according to claim 1, wherein the lid is formed with an opening penetrating the lid. The centrifugal compressor according to claim 2, wherein the area of the opening is smaller than the area of the through hole. The centrifugal compressor according to any one of claims 1 to 3, wherein the through hole communicates with a portion of the back surface outside the portion of the back surface where the counterbore portion and the portion of the rotation axis overlap in the axial direction and the counterbore portion. .. The centrifugal compressor according to any one of claims 1 to 3, wherein the through hole communicates with the counterbore portion, a portion of the back surface that overlaps the counterbore portion in the axial direction, and the counterbore portion.

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