JPH05272495A - Manufacture of impeller for centrifugal compression device - Google Patents

Abstract

PURPOSE:To cope with a three-dimensional passage becoming complicated in association with high speed and a high pressure ratio by forming an impeller in the divided state so as to provide hole like passages inside the outer peripheral surface of the impeller simply at low cost. CONSTITUTION:With the rotatory-driving of an impeller 22, refrigerant gas sucked from a suction port above a casing is discharged, while being compressed, outside the casing from a discharge port at the side of the casing through a passage. A method of manufacturing the impeller 22 of a centrifugal compression device of such constitution has a first process of providing plural grooves 35,... radially at the inner peripheral surface of an approximately umbrella shape shroud part 33; a second process of providing tenon protrusions 36 protrusively at the inner peripheral surface or the shroud part 33 corresponding to the parts between the mutually adjacent grooves 35, 35, whereas providing mortises 37 at the outer peripheral surface of an approximately conical hub part 31; and a third process of fitting the tenon protrusions 36,... to the mortises 37,... so that the outer peripheral surface 31a of the hub part 31 is crowned with the inner peripheral surface of the shroud part 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal compressor for compressing a fluid flowing in from an axial direction and transferring it in a radial direction, and more particularly, to an improvement of an impeller for compressing a fluid having a small flow rate.

[0002]

2. Description of the Related Art Generally, in a centrifugal compressor, a fluid suction port opened on the axial line of a casing, an axial direction extending from the suction port in the casing and then radially in the radial direction, and then the casing. A fluid flow passage communicating with a hollow annular portion formed in the inner radial direction, a fluid discharge port opened in the hollow annular portion, and slidably in the flow passage and on the axis of the casing. A plurality of blades having a positive pressure surface and a negative pressure surface, which are housed with a drive shaft, are provided with an impeller radially provided at predetermined intervals on the outer peripheral surface, and by the rotational driving of the blades on the outer peripheral surface of the impeller, The fluid sucked from the suction port is compressed between the outer peripheral surface of the impeller and the inner surface of the flow channel, transferred to the hollow annular portion through the flow channel, and discharged from the discharge port to the outside of the casing.

The blades provided on the open type impeller for compressing the fluid on the outer peripheral surface of the impeller are, for example, a turbo blower and a compressor (Showa 63).
As set out in the first edition, 1st printing issued by Corona Co., Ltd. on August 25, 2013, the optimal number of sheets is set in consideration of the flow rate of the fluid so as not to cause a pressure loss with the fluid due to an increase in the number of blades. ing.

As a centrifugal compressor impeller different from the one described above, there is also a closed type in which the fluid is compressed inside the outer peripheral surface of the impeller. This closed type impeller has an outer peripheral surface. Inwardly, a plurality of hole-shaped channels having an upstream end opened in the axial direction of the impeller and a downstream end opened in the radial direction orthogonal to the axis are provided at predetermined intervals along the outer peripheral surface. There is.

[0005]

By the way, when the above-mentioned closed type impeller is used in a centrifugal compressor or the like in which the flow rate of the fluid is small, the impeller itself is downsized, and thus the high speed of the centrifugal compressor is achieved. It is very difficult to process a three-dimensional hole-shaped flow path that is complicated by increasing the pressure and the pressure ratio. Moreover, in providing the above-mentioned hole-shaped flow path, if the impeller is manufactured by precision casting or the like, it becomes very expensive.

The present invention has been made in view of the above points, and an object of the present invention is to divide an impeller so that a hole-shaped flow passage can be easily and inexpensively provided inside the outer peripheral surface of the impeller. , It is to deal with the three-dimensional flow path that becomes complicated with the increase in speed and the increase in pressure ratio.

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned object, a solution means provided by the invention as claimed in claim 1 is a fluid suction port (5) opened on an axis (X) of a casing (2). When,
From the suction port (5), it extends in the casing (2) in the direction of the axis (X) and then in the radial direction, and communicates with the hollow annular portion (13) formed in the casing (2) in the radial direction. The fluid flow path (6), the fluid discharge port (15) opened in the hollow annular portion (13), the flow path (6), and the casing (2) axis ( X) is provided with a substantially conical impeller (22) having a drive shaft (21) on the flow path while compressing the fluid sucked from the suction port (5) by rotationally driving the impeller (22). Transfer to the hollow annular part (13) through (6)
The centrifugal compressor impeller (2) provided to the centrifugal compressor (1) that is made to discharge from the casing (2) from the (15)
As the manufacturing method of 2), the outer peripheral surface of the hub portion (31) having a substantially conical shape
(31a) or one of the inner peripheral surface (33a) of the substantially umbrella-shaped shroud portion (33) that is crowned with respect to the outer peripheral surface (31a) of the hub portion (31), the plurality of grooves (35), ... And a shroud part (3) of the hub part (31) corresponding to the first step of radially providing the predetermined intervals and the grooves (35), (35) adjacent to each other in the first step.
The inner surface of the shroud part (33) is attached to one of the inner surface (33a) of 3).
(33a) or the outer peripheral surface (31a) of the hub portion (33) is provided with a tenon protrusion (36) protruding to the other side, while the inner peripheral surface (33a) of the shroud portion (33) or the outer periphery of the hub portion (31) The second step of providing a mortise hole (37) into which the above-mentioned tenon protrusion (36) is fitted on the other side of the surface (31a), and the tenon protrusion (36), ...
7), fitted to the outer peripheral surface (31a) of the hub (31)
On the other hand, a third step of crowning the inner peripheral surface (33a) of the shroud portion (33) is adopted.

Further, the solution means taken by the invention of claim 2 limits the shapes of the mortise protrusions (36), ... And the mortise holes (37), ... Of the invention of claim 1, and the impeller (22 ) Axis
It is formed in a substantially linear shape when viewed from the direction orthogonal to (X).

Further, the solution means taken by the invention of claim 3 limits the shape of the grooves (35), ... Of the invention of claim 1 or 2, and the driving direction (Y) of the impeller (22) is limited. ), A positive pressure surface (38a) and a negative pressure surface (38b) facing each other are formed.

Further, the solution means taken by the invention of claim 4 limits the shape of the groove (35) of the invention of claim 3 and guides the fluid into the groove (35). The pressure surface (38a) at the end of the impeller (22) on the suction port (5) side.
Is formed on the taper surface (39) inclined with respect to the negative pressure surface (38b) and the tip of the taper surface (39) is located at the positive pressure surface on the discharge port (15) side of the impeller (22) with respect to the tip. Form a curved surface that gradually converges with respect to (38a).

[0011]

With the above construction, in the invention according to claim 1,
The impeller (22) is divided into a substantially conical hub portion (31) and a substantially umbrella-shaped shroud portion (33), and the outer peripheral surface (31) of the hub portion (31) is divided.
a) Or, after providing a plurality of grooves (35), ... on one of the inner peripheral surface (33a) of the shroud part (33) at predetermined intervals in a radial pattern,
The outer peripheral surface (3) of the hub (31) corresponding to the grooves (35), (35) adjacent to each other
1a) or the inner peripheral surface (33a) of the shroud part (33) and the tenon hole (37) provided on the other side are fitted to the tenon protrusion (36) of the hub part (31). The inner peripheral surface (33a) of the shroud part (33) is capped and integrally connected to the outer peripheral surface (31a) so that the fluid is compressed inside the outer peripheral surface (22a) of the impeller (22). The closed type impeller (22) will be constructed. As a result, in constructing a closed type impeller (22) used in a centrifugal compressor (1) where the flow rate of fluid is small, even if the impeller (22) itself is downsized, the impeller (22) The hole-shaped flow paths (34) provided inside the outer peripheral surface (22a) of the can be easily and inexpensively provided without depending on processing by drilling or manufacturing by precision casting.

According to the second aspect of the invention, the hub portion (3
1) outer surface (31a) or shroud (33) inner surface (33)
a) The tenon protrusions (36) provided on one side and the tenon holes (37) provided on the other side are the axis lines of the impeller (22).
The tenon projections (36), ... and tenon holes (37), ... are easily formed because they are formed in a substantially straight line when viewed from the direction orthogonal to (X), and the tenon projections (36), ... And Mortise (37),…
The manufacturing error of is as small as possible, and both (36),
(37) can be fitted smoothly.

According to the invention of claim 3, a plurality of grooves are provided.
(35), ... consist of a positive pressure surface (38a) and a negative pressure surface (38b) facing each other in the rotational drive direction (Y) of the impeller (22), so that the flow rate of the fluid is small. In the case of a centrifugal compressor (1), the impeller (22) is
By adopting a large width between (35) and (35), narrow grooves (35), ... Corresponding to a fluid having a small flow rate are formed.

Moreover, the above grooves (35), ... Are the grooves (35) ,.
Depending on the fluid flow rate per unit area that decreases in the inside, the width between the adjacent grooves (35), (35) is increased and the depth of the radial groove (35) of the impeller is increased. It becomes possible to correspond.

Further, in the invention according to claim 4, the positive pressure surface (38a) of the grooves (35), ... At the end of the impeller (22) on the suction port (5) side with respect to the negative pressure surface (38b). Inclined tapered surface (3
Since it is formed in the groove (9), the inflow angle of the fluid into the groove (35), ...
It is guided while being smoothly guided along 9). Moreover, since the tip of the tapered surface (39) is formed into a curved surface that gradually converges with respect to the positive pressure surface (38a) on the discharge port (15) side of the impeller (22), the groove ( 35), ... Inward tapered surface (39)
The fluid guided along the pressure surface (38a) of the impeller (22) does not separate from the pressure surface (38a) on the discharge port (15) side.
It will flow through the groove (35), ...

[0016]

As described above, according to the method of manufacturing an impeller for a centrifugal compressor in the invention described in claim 1, the outer peripheral surface (31a) of the hub portion (31) or the inner peripheral surface of the shroud portion (33).
(33a) After providing a plurality of grooves (35) on one side, the mortise projections (36), ... and the mortise holes (37), ... are fitted and divided (31), (33) Since the closed type impeller (22) is configured by integrally combining the two, even if the impeller (22) itself is downsized, a hole-like flow path is formed inside the outer peripheral surface (22a) of the impeller (22). (34), ... Can be provided easily and inexpensively, and thus can correspond to the three-dimensional flow paths (34), ... which become complicated as the centrifugal compressor (1) becomes faster and has a higher pressure ratio. be able to.

According to the method of manufacturing an impeller for a centrifugal compressor in the invention of claim 2, the tenon (3
6), ... and mortise (37), ... through the axis of the impeller (22)
Since it was formed in a substantially straight line when viewed from the direction orthogonal to (X),
The tenon protrusions (36), ... And the tenon holes (37), ... Can be easily formed. Moreover, the manufacturing error of the mortise protrusions (36), ... and the mortise holes (37), ... can be made as small as possible.
The fitting of 6) and (37) can be done smoothly.

According to the method of manufacturing an impeller for a centrifugal compressor in the invention of claim 3, a plurality of grooves (3
5), ... are composed of the pressure surface (38a) and the suction surface (38b) facing each other in the rotational driving direction (Y) of the impeller (22), so that the grooves (35), (35) adjacent to each other are formed. It is possible to form a narrow groove (35), ... corresponding to a small flow rate of fluid by taking a large width between them, and also to reduce the flow rate of the fluid per unit area in the groove (35), ... The groove (35) can also be deepened.

Further, according to the method of manufacturing an impeller for a centrifugal compressor in the invention of claim 4, the grooves (35), ...
The positive pressure surface (38a) of the groove (35) at the end on the suction port (5) side.
By forming the tapered surface (33) with a large angle of inflow of fluid into the inside and forming the tapered surface of the tapered surface (39) into a gradually converged curved surface, the smooth inside of the groove (35) ,. The fluid guided to the inside can be circulated in the grooves (35), ... along the tapered surface (39) all the time, and the compression efficiency of the fluid can be improved.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

As shown in FIG. 1, (1) is a centrifugal compressor used in a small refrigerating machine or the like for compressing and discharging a refrigerant gas.

The centrifugal compressor (1) comprises a centrifugal compression mechanism (3) and a drive motor (4) in a substantially cylindrical hermetic casing (2). On the upper end surface (2a) on the axis (X) of the casing (2), a suction port (5) communicating with a low pressure chamber (not shown) is opened. Further, in the casing (2), a flow path for guiding the refrigerant gas sucked from the suction port (5) to a discharge port (15) described later.
(6) is formed.

The flow channel (6) includes a first flow channel (11) extending from the suction port (5) in the casing (2) in the direction of the axis (X), and a tip portion of the first flow channel (11). (11a) (lower end in the figure), the axis of the casing (2) at its tip (11a)
A second flow path (12) that radially expands in the radial direction around (X) and is communicated with the outer peripheral edge of the second flow path (12),
Casing at the tip (11a) of the first flow path (11)
It is composed of a hollow annular portion (13) arranged at the peripheral edge of the casing (2) centering on the axis (X) of (2). Further, the hollow annular portion (13) is provided with a chamber (14) in which the flow passage cross-sectional area of the hollow annular portion (13) is enlarged.
A discharge port (15) is opened at (14). The discharge port (15)
Communicate with a high-pressure chamber (not shown) through a side surface (2b) orthogonal to the axis (X) of the casing (2).

In the vicinity of the tip portion (11a) of the first flow channel (11), the hem is widened so as to converge to the second flow channel (12) side, and formed into a substantially triangular shape. A substantially conical impeller (22) having a drive shaft (21) on the axis (X) of the casing (2) is housed in the vicinity of the tip (11a) of the one flow path (11). The drive shaft (21) is extended to the bottom of the casing (2), and its base end (upper end in the figure) and tip (lower end in the figure) have a shaft hole (23) in the casing (2). , (2
It is rotatably fitted in the bearing 4 through the bearings 25, 26. The intermediate portion of the drive shaft (21) is fitted and inserted in the rotor (4a) of the drive motor (4). Further, the stator (4b) of the drive motor (4) is attached to the lower portion of the casing (2). The inner surface (6a) of the flow channel (6), that is, the inner surface (27) near the tip (11a) of the first flow channel (11) and the proximal end (12a) of the second flow channel (12). The inner surface (28) is curved along the outer peripheral surface (22a) of the impeller (22) so as to be in sliding contact with the outer peripheral surface (22a) of the impeller (22). Surface (22a) and flow path
Inner surface (6a) of (6) (inner surface (27) near the tip (11a) of the first channel (11) and inner surface (28) near the proximal end (12a) of the second channel (12)) Impeller (22) not shown between
The outer peripheral surface (22a) forms a sliding space (gap) that can slide with respect to the inner surface (6a) of the flow path (6). In this case, when the impeller (22) is rotationally driven by the drive motor (4), the low-pressure refrigerant gas sucked from the suction port (5) through the first flow path (11) causes the impeller (22) to be described later. Compressed into a plurality of grooves (35) inside the outer peripheral surface (22a), the high pressure refrigerant gas is transferred to the hollow annular portion (13) through the second flow path (12). Then, the gas is discharged from the discharge port (15) through the chamber (14) to the outside of the casing (2) (high-pressure chamber side).

Then, as shown in FIGS. 2 to 4,
As the impeller (22), a closed type impeller (22) is used which compresses the refrigerant gas inside the outer peripheral surface (22a). The impeller (22) includes a hub portion (31) having a substantially conical shape and a substantially umbrella-shaped shroud (33) for crowning an inner peripheral surface (33a) with an outer peripheral surface (31a) of the hub portion (31). ) And are divided into. In addition, the inner peripheral surface (33
In a), the inner surface of the outer peripheral surface (22a) of the impeller (22) formed by coupling the hub portion (31) and the shroud (33),
Outer peripheral surface (31a) of hub (31) and inner peripheral surface of shroud (33)
A plurality of grooves (35) forming the main flow path (34) for the refrigerant gas are provided in a radial pattern with respect to (33a) at predetermined intervals. The grooves (35), ... Are formed in the shape of a hole having an upstream end opened in the axis (X) direction of the impeller (22) and a downstream end opened in the radial direction orthogonal to the axis (X). Become.
Further, among the plurality of grooves (35), ..., Adjacent grooves (35),
The inner peripheral surface (33a) of the shroud part (33) corresponding to the space (35) has a mortise protrusion (3a) protruding toward the outer peripheral surface (31a) of the hub part (31).
6) are provided radially along the inner peripheral surface (33a).
On the other hand, on the outer peripheral surface (31a) of the hub portion (31) corresponding to the grooves (35), (35) adjacent to each other, the mortise hole (3
7) are provided radially along the outer peripheral surface (31a).
And, each groove (35) is in the rotational driving direction of the impeller (22).
The pressure surface (3
8a) and the negative pressure surface (38b), and the bottom surface (38c) connecting the opposing surfaces (38a) and (38b). In addition, the groove (3
5) is to guide the refrigerant gas into the grooves (35), ...
It is formed on the suction port (5) side end of the impeller (22), that is, the positive pressure surface (38a) at the upstream end is a tapered surface (39) inclined by β ° with respect to the base end of the negative pressure surface (38b). , The tapered surface (39)
Near the tip of the impeller than the tip of the tapered surface (39).
It is formed into a curved surface that gradually converges with respect to the discharge port (15) side of (22), that is, the positive pressure surface (38a) on the downstream side.

In this case, the centrifugal compressor (1) has a suction port.
The volume flow rate of the refrigerant gas flowing between (5) and the discharge port (15) per unit time is a few m ³ / h to several tens m ³ / h, which is a small flow type and is used as an impeller (22). Is 30 mm to 60 mm at the outermost portion of the outermost diameter on the downstream side.
Something is used. Further, the grooves (35), ... Within the outer peripheral surface (22a) of the impeller (22), that is, on the inner peripheral surface (33a) of the shroud (33), have a deep groove depth on the upstream side of the impeller (22). While the refrigerant gas smoothly flows in, the groove depth on the downstream side of the impeller (22) is shallow according to the flow passage cross-sectional shape of the second flow passage (12) (for example, 2 mm to 3 mm). Degree) formed second channel of refrigerant gas
The outflow to the (12) side is done smoothly.

Here, the impeller (2) for the centrifugal compressor (1)
The manufacturing method of 2) will be described. As the impeller (22), a material such as aluminum or ceramics, which is advantageous in reducing the inertial weight, is used.

First, in the first step, the hub portion (31) is formed in a substantially conical shape, and the shroud portion (33) is formed in a substantially umbrella shape to divide the impeller (22). A plurality of grooves (35) are radially provided at predetermined intervals on the inner peripheral surface (33a) of the shroud portion (33).

Then, in the second step, the hub portion (31) is attached to the inner peripheral surface (33a) of the shroud portion (33) corresponding to the grooves (35), (35) adjacent to each other in the first step. A tenon protrusion (36) protruding toward the outer peripheral surface (31a) is provided. On the other hand, the tenon protrusion (36) is formed on the outer peripheral surface (31a) of the hub portion (31) between the adjacent grooves (35), (35).
Provide a mortise (37) to fit in.

Then, in a third step, the tenon protrusions (36), ... According to the second step are fitted into the mortise holes (37) ,, and the outer peripheral surface (31a) of the hub portion (31) is then fitted. By crowning the inner peripheral surface (32a) of the shroud part (33) with respect to the hub part
(31) and the shroud part (33) are combined to form an integral impeller (22).

As described above, in the above embodiment, the plurality of grooves (35), ... Are provided on the inner peripheral surface (33a) of the shroud portion (33), and then the tenon protrusions (36) ,. ), ... and are divided by fitting them together (31), (33)
A closed type impeller (22) is configured to compress the refrigerant gas inside the outer peripheral surface (22a) of the impeller (22). As a result, the volumetric flow rate of the refrigerant gas flowing between the suction port (5) and the discharge port (15) per unit time is several meters.
³ / h to several tens of ^m 3 / h about the low flow-type centrifugal compressor of
In constructing the closed-type impeller (22) used in (1), even if the impeller (22) itself is downsized, a hole-shaped flow is provided inside the outer peripheral surface (22a) of the impeller (22). Road
(34), ... Can be easily and inexpensively provided without depending on the processing by drilling or the production by precision casting, etc. Therefore, as the centrifugal compressor (1) becomes faster and has a higher pressure ratio, It is possible to deal with complicated three-dimensional flow paths (34), ....

Further, the tenon protrusions (36) provided on the inner peripheral surface (33a) of the shroud portion (33) and the mortise holes (37) provided on the outer peripheral surface (31a) of the hub portion (31). But the impeller (22)
The tenon protrusions (36), ... And the tenon holes (37), ... Can be easily formed because they are formed in a substantially straight line shape when viewed from the direction orthogonal to the axis line (X). Moreover, the mortise protrusions (36),
And the mortises (37), ... Can be made as small as possible in manufacturing error, and the two (36), (37) can be fitted smoothly.

Further, the plurality of grooves (35), ...
It consists of a positive pressure surface (38a) and a negative pressure surface (38b) facing each other in the rotational drive direction (Y) of 2), so that the centrifugal compressor (1 )
However, the impeller (22) must be formed with narrow grooves (35), ... Corresponding to the refrigerant gas with a small flow rate by increasing the width between the adjacent grooves (35), (35). You can Moreover, the above-mentioned grooves (35), ... Establish a width between the adjacent grooves (35), (35) in accordance with the amount of refrigerant gas flowing per unit area which decreases in the grooves (35) ,. It is possible to increase the depth of the groove (35) in the radial direction of the impeller (22) while adopting a large amount, and thus it is possible to form the grooves (35), ... According to the flow rate of the refrigerant gas.

Moreover, the groove (35) is formed on the taper surface (39) in which the positive pressure surface (38a) at the upstream end of the impeller (22) is inclined by β ° with respect to the negative pressure surface (38b). Groove (35),…
The inflow angle of the refrigerant gas into the inside is greatly expanded, and the groove (35),
The refrigerant gas is guided into the inside while being smoothly guided along the tapered surface (39). Moreover, since the vicinity of the tip of the tapered surface (39) is formed into a curved surface that gradually converges with respect to the positive pressure surface (38a) on the downstream side of the impeller (22) with respect to the tip of the tapered surface (39), Refrigerant gas introduced along the tapered surface (39) into the grooves (35), ... is not separated from the positive pressure surface (38a) on the downstream side of the impeller (22), and then flows onto the positive pressure surface (38a). It can be circulated in the grooves (35), ... As a result,
The refrigerant gas can be efficiently compressed.

The present invention is not limited to the above embodiments, but includes various other modifications.
For example, in the above embodiment, the inner peripheral surface (3
Although the grooves (35), ... Are provided in 3a), a plurality of grooves may be provided in a radial pattern on the outer peripheral surface of the hub portion.

Further, in the above embodiment, the shroud portion (33)
The tenon protrusions (36) are provided on the inner peripheral surface (33a) of the above, but the tenon protrusions may be provided on the outer peripheral surface of the hub portion corresponding to the adjacent grooves. In this case, the mortise grooves (37) provided on the outer peripheral surface (31a) of the hub portion (31) are provided on the inner peripheral surface of the shroud portion corresponding to the adjacent grooves.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an impeller.

FIG. 2 is a vertical cross-sectional view before fitting of an impeller, which is cut along a groove.

FIG. 3 is a cross-sectional view of the upstream side of the impeller, which is partially cut and before the impeller is fitted.

FIG. 4 is a cross-sectional view after the impeller of FIG. 3 is fitted.

FIG. 5 is a vertical cross-sectional view of a centrifugal compression device.

[Explanation of symbols]

 (1) Centrifugal compressor (2) Casing (5) Suction port (6) Flow path (13) Hollow annular part (15) Discharge port (21) Drive shaft (22) Impeller (31) Hub part (31a) Outer circumference Surface (33) Shroud part (33a) Inner surface (35) Groove (36) Mortise protrusion (37) Mortise hole (38a) Pressure surface (38b) Suction surface (39) Tapered surface (X) Impeller axis (Y) Rotational drive direction of impeller

Claims (4)

[Claims] 1. A fluid suction port (5) opened on the axis (X) of the casing (2), and a casing (2) from the suction port (5).
A flow path (6) for the fluid, which extends in the axial direction (X) and then radially in the radial direction, and communicates with the hollow annular portion (13) formed in the radial direction in the casing (2), Fluid discharge port (15) opened in the hollow annular portion (13), and the flow path (6)
And a substantially conical impeller (22) that is housed in the casing (2) and has a drive shaft (21) on the axis (X) of the casing (2), and the suction port ( 5) The hollow annular part is compressed through the flow path (6) while compressing the fluid sucked from
In the manufacturing method of the centrifugal compressor impeller (22) to be used in the centrifugal compressor (1), which is transferred to the (13) and discharged from the discharge port (15) to the outside of the casing (2), Outer peripheral surface (31a) of hub (31), which is approximately conical, or hub
A plurality of grooves (35) are arranged at predetermined intervals on one side of the inner peripheral surface (33a) of the substantially umbrella-shaped shroud portion (33) that is crowned with respect to the outer peripheral surface (31a) of (31). In the first step, and the hub portion (3) corresponding to the grooves (35), (35) adjacent to each other in the first step.
1) outer surface (31a) or shroud (33) inner surface (33)
a) on one side, the mortise protrusion (3a) protruding to the other side of the inner peripheral surface (33a) of the shroud part (33) or the outer peripheral surface (31a) of the hub part (31).
6) is provided, the above-mentioned tenon protrusion (36) is provided on the other of the inner peripheral surface (33a) of the shroud part (33) or the outer peripheral surface (31a) of the hub part (31).
A second step of providing a mortise (37) for fitting the mortise (37) to the mortise (37), ... A third step of crowning the inner peripheral surface (33a) of the shroud portion (33) with respect to the outer peripheral surface (31a), the impeller for a centrifugal compressor. 2. Mortise projections (36), ... and mortise holes (37) ,.
The method for manufacturing an impeller for a centrifugal compressor according to claim 1, wherein the impeller (22) is formed in a substantially linear shape when viewed from a direction orthogonal to an axis (X) of the impeller (22). 3. The grooves (35), ... Forming a positive pressure surface (38a) and a negative pressure surface (38b) facing each other in the rotational driving direction (Y) of the impeller (22). The method for manufacturing an impeller for a centrifugal compressor according to claim 1 or 2. 4. The positive pressure surface (38a) at the end of the impeller (22) on the suction port (5) side is provided so that the groove (35), ... Is a guide for guiding the fluid into the groove (35) ,. , A taper surface (39) that is inclined with respect to the negative pressure surface (38b) and the tip of the taper surface (39) is located at the positive pressure surface (side) of the impeller (22) closer to the discharge port (15) than the tip. The method of manufacturing an impeller for a centrifugal compressor according to claim 3, wherein the curved surface is gradually converged with respect to 38a).