JPH10141293A - Centrifugal fluid machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operating efficiency by reducing flow loss in a centrifugal fluid machinery. SOLUTION: An open-type impeller 4 in which blades 41, 41,... are exposed is rotated, gaseous refrigerant sucked from a suction passage 3e so opened as to face the blade surface 4a is allowed to flow outward in the radial direction along the blade surface, and a casing shroud 3d close arranged so as to cover the blade surface from the opened part of the suction passage to the outer peripheral side of the impeler is provided on a turbocompressor for compressing gaseous refrigerant in a compression chamber so provided as to surround the impeller and for discharging it. A clearance between the blade surface 41 and the casing shroud 3d is set to a value obtained by adding the deformation amounts H1 (r, z) in relation to the casing shroud for every radial parts, to be generated in the rotational operation of the impeller to the preset required minimum clearance values H2+H3+H4+H5 for every radial part of the blade surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open impeller having an exposed blade, wherein the rotation of the impeller causes the fluid sucked from the suction side to flow outwardly in the radial direction of the impeller to discharge the impeller. More specifically, the present invention relates to a centrifugal fluid machine such as a turbo compressor which is used in a refrigerant circuit of an air conditioner and compresses and discharges a refrigerant gas.

[0002]

2. Description of the Related Art Conventionally, as a centrifugal fluid machine of this type, as shown in FIG. 5, an impeller (4) is driven to rotate by an electric motor (2) and a refrigerant gas sucked from a suction passage (30e) is removed. There is known a turbo compressor which discharges from a discharge passage (33) after being compressed. In this device, an open impeller (4) having exposed blades (41, 41,...) (See FIG. 6) is used, and a suction passage (30) is used.
e) The refrigerant gas sucked from e) flows radially outward along the blade surface (4a) of the impeller (4), and the compression chamber (3) disposed around the outer periphery of the impeller (3).
In order to efficiently flow the refrigerant gas along the blade surface (4a),
Impeller casing (30) for housing impeller (4)
A shroud portion (30d) serving as a casing shroud is formed in a portion of the first portion facing the blade surface (4a). Here, in the turbo compressor,
Since there is a flow loss proportional to a radial cross-sectional area (hereinafter simply referred to as a gap area) of a gap between the blade surface (4a) of the impeller (4) and the shroud portion (30d), the gap needs to be reduced as much as possible. On the other hand, in consideration of errors caused by processing accuracy, assembly accuracy, and the like, even when those errors are maximized, the gap amount does not become zero, that is, the impeller (4) and the shroud portion (30d). Should not be in contact with Therefore, in the above-described conventional turbo compressor, as shown by a solid line in FIG. 6, when the impeller (4) is in the stopped state, the impeller (4)
The gap between the impeller (4) and the shroud (30d) is uniformly set to the following set gap (H) from the inner circumference (4c) to the outer circumference (4d).

That is, H = H1max + H2
+ H3 + H4 + H5 Here, H1max is the maximum deformation amount at the part of the impeller (4) that deforms the most (in the illustrated example, the outer peripheral part (4d) of the impeller), and H2 is the machining tolerance. H3 is an assembly tolerance, H4 is a design value of a gap amount, and H5 is a safety margin. That is, the value obtained by adding the deformation amount (H1max) of the impeller (4) to the required minimum gap amount (H2 + H3 + H4 + H5) is set as the set gap amount.

[0004]

However, in the above-mentioned conventional turbo compressor, as shown by a virtual line in FIG.
When the impeller (4) is in a rotating state, the outer peripheral portion (4d) of the impeller (4) is deformed toward the shroud portion (30d) by the maximum deformation amount (H1max) due to centrifugal force or the like, and the outer peripheral portion (4d) is deformed. ), The gap amount with the shroud portion (30d) becomes the optimum gap amount (H2 + H3 + H4 + H5), but the inner peripheral portion (4c) of the impeller (4) is connected to the drive shaft (21) of the electric motor (2). Since the blade surface (4a) and the shroud portion (30) are connected to each other and hardly deformed,
d) is equal to the required minimum clearance (H2 + H3 + H)
4 + H5), which results in a disadvantage that the flow loss is increased and the compression efficiency, that is, the operation efficiency is reduced.

[0005] The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the flow loss of a centrifugal fluid machine and improve the operation efficiency thereof.

[0006]

In order to achieve the above object, the invention according to claim 1 comprises a plurality of blades (41, 4) radially arranged radially about a rotation axis (X).
An impeller (4) having a radial direction outward by rotating the impeller (4), and a suction passage (3e) opened on the rotating shaft (X) so as to face the impeller (4). And a blade surface (4a) of each of the blades (41) on the suction passage (3e) side is disposed so as to cover from the opening of the suction passage (3e) to the outer peripheral side of the impeller (4). A casing shroud (3d), and a discharge passage (33) opened to face the outer peripheral portion (4d) of the impeller (4), and by rotation of the impeller (4),
It is assumed that a centrifugal fluid machine discharges the fluid sucked from the suction passage (3e) from the discharge passage (33).
In this case, the casing shroud (3d)
The gap between the impeller (4) and the blade surface (4a) is defined by a required minimum clearance (H2 + H3 + H4 + H5) preset for each radial portion of the blade surface (4a). The amount of deformation (H) with respect to the casing shroud (3d) at each radial position generated during the rotation operation
1 (r, z)).

In the above configuration, the fluid sucked from the suction passage (3e) by the rotation of the impeller (4) is sent radially outward along the blade surface (4a) of the impeller (4). . At this time, the impeller (4) deforms with its rotation, so that the amount of clearance between the impeller (4) and the casing shroud (3d) is uniform at each radial position of the impeller (4). (H2 + H3 + H4 + H5). Therefore, when the impeller (4) is in a rotating state, the gap area between the impeller (4) and the casing shroud (3d) can be reduced as compared with the conventional case, so that the flow loss of the centrifugal fluid machine can be reduced. As a result, it is possible to improve the operation efficiency of the centrifugal fluid machine.

According to a second aspect of the present invention, in the first aspect of the present invention, the impeller (4) is disposed annularly around the outer periphery of the impeller (4), and the suction passage (3) is rotated by rotation of the impeller (4).
e) a configuration including a compression chamber (32) for compressing the fluid sucked in from e).

In the case of the above configuration, a centrifugal fluid machine is specifically specified as a centrifugal compressor for compressing a fluid. And in this centrifugal compressor, it is possible to reduce the flow resistance in the gap between the impeller (4) and the casing shroud (3d) when the impeller (4) is in a rotating state, thereby improving the compression efficiency. become.

According to a third aspect of the present invention, the tensile strength of the impeller (4) in the radially outward direction in the first or second aspect of the invention is defined by the suction passage (3e) with respect to the rotation axis (X) direction. ) Is configured to be smaller on the opposite side than on the side.

In the case of the above configuration, the amount of tensile deformation of the rotating impeller (4) radially outward due to centrifugal force is determined by the radial tensile strength of the impeller (4) being the rotation axis (X). ) Direction, it is relatively large on the blade surface (4a) side, so that it is relatively small on the blade surface (4a) side. For this reason, when the impeller (4) is rotated, the outer peripheral portion (4d) of the impeller (4)
It will bend and deform and approach the d) side. That is, the direction of deformation of the outer peripheral portion (4d) during the rotation operation of the impeller (4) can be surely directed to the casing shroud (3d) side. The operation according to the invention described in Item 2 can be reliably obtained.

According to a fourth aspect of the present invention, a through hole (42) in which the drive shaft (21) is internally fitted to the impeller (4) according to the third aspect of the invention is formed along the rotation axis (X), The inner diameter of the through hole (42) is set to be larger on the side opposite to the blade surface (4a) with respect to the rotation axis (X).

In the case of the above configuration, the configuration of the impeller (4) for realizing the invention described in claim 3 is specifically specified.
That is, the impeller (4) is formed with a through hole (42) into which the drive shaft (21) is fitted, and the inner diameter of the through hole (42) is set relatively small on the blade surface (4a) side. Therefore, the radial tensile strength of the impeller (4) becomes relatively large on the blade surface (4a) side, and therefore, the impeller (4) is bent toward the blade surface (4a) by centrifugal force. It can be deformed.
That is, the radial tensile strength of the impeller (4) can be easily and reliably set by setting the inner diameter of the through hole (42) formed for coupling with the drive shaft (21). Thereby, the operation according to the third aspect of the invention can be reliably obtained.

According to a fifth aspect of the present invention, in the second aspect, the impeller (4) has a blade surface (4
a) and a pressurizing chamber (34) is disposed on the opposite side of the direction of the rotation axis (X), and the pressurizing chamber (34) communicates with the compression chamber (32) so that the fluid in the compression chamber (32) Pressure is applied to the impeller (4), and the impeller (4) is coupled to the drive shaft (21) on the inner peripheral side. Then, the pressure receiving surface (4b) of the impeller (4) facing the pressure chamber (34) is moved in the direction of the rotation axis (X) by the fluid pressure in the pressure chamber (34) acting on the pressure receiving surface (4b). The pressing force is set to an area that is larger than the pressing force in the direction of the rotation axis (X) due to the fluid pressure acting on the blade surface (4a).

In the above configuration, the high-pressure fluid compressed in the compression chamber (32) flows through the compression chamber (34) as the impeller (4) rotates, and the high-pressure fluid causes the impeller (4) to rotate. ) From the pressure receiving surface (4b) side. Here, since the pressing force by the fluid pressure acting on the pressure receiving surface (4b) is made larger than the pressing force by the fluid pressure acting on the blade surface (4a), the impeller (4) receives the pressure. From the surface (4b) side, the blade surface (4
a) It is pressed to the side. Further, since the impeller (4) is connected to the drive shaft (21) on the inner peripheral side, the outer peripheral side of the impeller (4) is connected to the casing shroud (3).
d) side. In other words, with a configuration different from the third aspect, the direction of deformation of the outer peripheral portion (4d) during the rotation operation of the impeller (4) can be reliably directed to the casing shroud (3d) side. This makes it possible to reliably obtain the operation according to the second aspect of the present invention.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a turbo compressor (centrifugal compressor) as a centrifugal fluid machine according to an embodiment of the present invention,
Reference numeral 10 denotes a compression mechanism for sucking and compressing a refrigerant gas as a fluid, and reference numeral 20 denotes a drive mechanism for operating the compression mechanism (10). In this drive mechanism (20), 1
Is a motor casing, 2 is this motor casing (1)
An electric motor housed in the housing; and in the compression mechanism (10), reference numeral 3 denotes the motor casing (1).
An impeller casing 4 disposed at one end of the motor is an impeller driven to rotate by the electric motor (2).

The motor casing (1) is formed into a cylindrical peripheral wall (11) and a thick disk having a diameter larger than that of the peripheral wall (11). The first partition wall (12) and the bottom wall (13) disposed coaxially at both upper and lower ends (hereinafter, simply referred to as upper and lower sides) of the above have a substantially cylindrical shape. In addition, the first partition (1)
2) Through hole (12a) with a circular cross section in the center in plan view
Is formed and the through hole (12a) is formed on the upper surface.
A concave portion (12b) having a circular cross section larger in diameter than the through hole (12a) is formed coaxially with the through hole (12a). A concave portion (13a) having the same diameter as the circular cross section is formed. Reference numerals 16 and 17 denote flow passages disposed on the upper and lower ends of the peripheral wall portion (11) for flowing the refrigerant gas to cool the electric motor (2).

The electric motor (2) has its proximal end inserted into the recess (13a) of the bottom wall (13), and its distal end inserted through the through hole (12a) of the first partition (12). , A rotor (22) arranged on the outer peripheral surface of the drive shaft (21), and an inner surface of the peripheral wall (11) opposed to the rotor (22). And a stator (23) provided. In addition, the drive shaft (2
1) is supported by dynamic pressure journal gas bearings (21a, 21b) disposed at portions surrounded by the through-hole (12a) and the recess (13a), and is integrally fixed to the outer peripheral surface on the distal end side. And a disc-shaped bearing plate (14) housed in the recess (12b) of the first partition (12).
The bearing is supported by a dynamic pressure thrust gas bearing (14a) disposed on the base end surface, and a protection bearing (21c) for supporting the drive shaft (21) when the driving shaft (21) is in a stopped state is disposed on the base end face. I have.

The impeller casing (3) has an annular bottom wall (3a) having the same outer diameter as the outer diameter of the first partition (12), and an annular ring extending upward from the bottom wall (3a). Outer wall portion (3b), an annular inner wall portion (3c) that is gently folded from the upper end side of the outer wall portion (3b) and extends downward on the inner circumference side, and a lower end of the inner wall portion (3c) An annular shroud portion (3d) as a casing shroud that is folded back from the edge and extends upward on the inner peripheral side, and a tube that extends upward from an upper end edge of the shroud portion (3d) and communicates with a low-pressure side conduit (not shown). The suction passage (3e)
It has a substantially frustoconical shape projecting upward. And
The impeller casing (3) is coaxially fixed on the lower surface of the bottom wall portion (3a) on the upper surface of the first partition wall portion (12), and has a disk-like shape fitted inside the bottom wall portion (3a). Together with the two partition walls (15), an impeller chamber (31) for accommodating the impeller (4) is formed. Further, a through hole (15a) is formed at the center of the second partition (15) in plan view, and the drive shaft (21) of the electric motor (2) is inserted therethrough.
The impeller (4) is integrally connected to the tip of the drive shaft (21).

The impeller chamber (31) includes an annular compression chamber (32) surrounded by the bottom wall (3a), the outer peripheral wall (3b) and the inner peripheral wall (3c) on the outer peripheral side thereof. The discharge passage (33) opening toward the compression chamber (32) communicates with a high-pressure side conduit (not shown). The through hole (15a) is provided on the upper surface of the second partition (15).
A concave portion (15b) having a circular cross section slightly larger than the outer diameter of the impeller (4) is formed coaxially with the impeller (4).
The through hole (15a) and the drive shaft (2) of the electric motor (2)
A seal portion for preventing leakage of the refrigerant gas is provided between the pressure chamber (1) and the annular pressurizing chamber (3) by the concave portion (15b) and the bottom surface (4b) as a pressure receiving surface of the impeller (4).
4) is formed. The pressurizing chamber (34) communicates with the compression chamber (32) on the outer peripheral side, and the compression chamber (32)
A high-pressure (PH) refrigerant gas (see FIG. 4) compressed by the above-described method is introduced, and the gas pressure of the refrigerant gas is applied to the bottom surface (4b) of the impeller (4). . Further, the area of the bottom surface (4b) of the impeller (4) is such that the upward pressing force due to the gas pressure acting on the bottom surface (4b) is reduced by the downward pressing force due to the refrigerant gas acting on the blade surface (4a) described later. Therefore, the direction of the bending deformation of the impeller (4) in the rotating state is such that the outer peripheral portion (4d) of the impeller (4d) is shroud as shown by an imaginary line in FIG. Part (3d)
It becomes a direction approaching the side.

As shown in FIG. 2, the impeller (4) is formed in a substantially truncated cone shape, and blades (41, 41,...) For flowing the refrigerant gas radially around its inclined surface. The blade surface (4a) is arranged to form a through hole (42) (see FIG. 3) along the rotation axis (X) from the blade surface (4a) to the opposite bottom surface (4b). Is formed. Then, the tip of the drive shaft (21) is press-fitted into the through hole (42) from the bottom surface (4b) side, and the drive shaft (21) and the impeller (4) are integrally connected. When the impeller (4) is rotationally driven by the shaft (21), the refrigerant gas sucked from the suction passage (3e) is subjected to the blade surface (4) of the impeller (3).
It is adapted to be sent to the outer peripheral side along a).

The inner diameter of the through hole (42) formed through the impeller (4) is made smaller (d1) on the blade surface (4a) side, while it is made larger diameter (d2) on the bottom surface (4b) side.
Therefore, the radially outward tensile strength of the impeller (4) is larger on the blade surface (4a) side than on the bottom surface (4b) side. Therefore, the impeller (4) has a blade surface (4a) due to a tensile stress generated radially outward due to centrifugal force in a rotating state.
The tensile deformation is larger on the bottom surface (4b) side than on the side surface, and as a result, as shown by the phantom line in FIG. 3, the blade is deformed toward the blade surface (4a) side.

The setting of the clearance (H (r, z)) between the shroud portion (3d) of the impeller casing (3) and the blade surface (4a) of the impeller (4) will be described below with reference to FIG.
It will be described based on.

The shape of the inner surface of the shroud portion (3d) is such that the gap amount (H (r, z)) between the shroud portion (3d) and the blade surface (4a) depends on the rotation of the impeller (4). It is set to be uniform at each part in the radial direction. That is, due to the centrifugal force or the like acting on the impeller (4) due to the rotation of the impeller (4), each part of the impeller (4) has a distance (r) from the rotation axis (X) and the impeller (4). In consideration of the deformation according to the thickness (z), the gap between the shroud portion (3d) and the blade surface (4a) of the impeller (4) depends on the distance (r) and the thickness (z). As a result, during the rotation of the impeller (4), the amount of clearance between the shroud (3d) and the shroud (3d) at each radial position of the impeller (4) is made uniform. ing.
Specifically, the gap amount (H (r, z)) is set as shown in the following equation.

That is, H (r, z) = H1 (r, z)
+ H2 + H3 + H4 + H5 where H1 (r, z) is a distance (r) from the rotation axis (X).
This is the amount of upward deformation of each part of the impeller (4) separated by only a distance, and is due to bending deformation due to centrifugal force or the like acting on the impeller (4). H2 is a processing tolerance, H3 is an assembly tolerance, H4 is a design value of a clearance, and H5 is a safety margin. In other words, the value obtained by adding the deformation (H1 (r, z)) in each part of the impeller (4) to the required minimum gap (H2 + H3 + H4 + H5) is set as the set gap.

With such a setting, the gap amount (H (r, z)) between the blade surface (4a) of the impeller (4) and the shroud portion (3d) stops the impeller (4). In the state, the required minimum gap amount (H2 + H3 + H4 + H5) is uniformly uniform in the circumferential direction at the inner peripheral portion (4c).
), While gradually increasing outward in the radial direction and reaching a maximum at the outer peripheral portion (4d).

Next, the operation of the turbo compressor according to the above-described embodiment and its operation and effects will be described.

First, the electric motor (2) is operated to rotate the impeller (4) in a stopped state. With the rotation of the impeller (4), each part thereof becomes a shroud part (3
At this time, the gap between the blade portion (4a) and the shroud portion (3d) of the impeller (4) becomes smaller than the required minimum gap (H2 + H3 + H) at each radial position.
4 + H5), and the contact between the impeller (4) and the shroud (3d) is reliably prevented.

When the impeller (4) rotates,
Refrigerant gas is sucked from the suction passage (3e), is sent to the outer peripheral side along the blade surface (4a) of the impeller (4), is compressed in the compression chamber (32), and is then discharged to the discharge passage (3).
It is discharged from 3). At this time, as shown in FIG. 4, the gas pressure of the refrigerant gas flowing along the blade surface (4a) gradually increases from a low pressure (PL) to a high pressure (PH) toward the outer peripheral side, and the gas pressure increases. Causes a downward pressing force to be applied to the blade surface (4a).
A part of the refrigerant gas compressed in the compression chamber (32) flows to the pressurization chamber (34) and the bottom surface (4b) of the impeller (4).
, An upward pressing force slightly larger than the downward pressing force is applied to bend the impeller (4) slightly upward. For this reason, the impeller (4) is bent and deformed toward the shroud portion (3d) due to centrifugal force caused by its rotation, and the gap between the impeller (4) and the shroud portion (3d) at each portion in the rotating state. Becomes the required minimum gap amount (H2 + H3 + H4 + H5) uniformly (see FIG. 2). Therefore, the blade surface (4) of the impeller (4)
The gap area between a) and the shroud portion (3d) can be reduced as compared with the conventional one, whereby the flow loss of the turbo compressor can be reduced and the compression efficiency can be improved.

In the turbo compressor, the impeller (4) in a rotating state is bent and deformed toward the blade surface (4a), so that the impeller (4) is driven by the drive shaft (21) of the electric motor (2). By setting the inner diameter of the through hole (42) formed for press-fitting on the blade surface side relatively smaller than the bottom surface (4b) side, the radial tensile strength of the impeller (4) can be reduced. It is configured to be larger on the blade surface (4a) side than on the 4b) side. That is, by setting the inner diameter of the through hole (42), the direction of the bending deformation of the impeller (4) can be easily and reliably set on the blade surface (4a) side. Further, the refrigerant gas compressed in the compression chamber (32) is transferred to the impeller (4).
To the bottom face (4a) of the above to apply an upward pressing force to the impeller (4) by the gas pressure.
The direction of the bending deformation by the gas pressure of the impeller (4) can be set with a relatively simple configuration without providing a dedicated gas pressure source or the like.

<Other Embodiments> The present invention is not limited to the above embodiments, but includes various other embodiments. That is, in the above embodiment,
The amount of clearance between the impeller (4) and the shroud (3d)
Although the setting is made according to the shape of the shroud portion (3d), the present invention is not limited to this, and the gap amount may be set according to the shape of the impeller, for example.

In the above embodiment, by setting the inner diameter of the through hole (42) formed in the impeller (4), the impeller (4) is bent toward the blade surface (4a) by centrifugal force. The impeller (4) is pressed against the blade surface (4a) by the gas pressure of the refrigerant gas guided from the compression chamber (32). However, the present invention is not limited to this. As a means for setting the predetermined direction, only one of the setting of the inner diameter of the through hole (42) or the setting of the pressing force by the gas pressure may be used.

In the above embodiment, the inner diameter of the through hole (42) formed in the impeller (4) is set to be larger on the bottom surface (4b) side than on the blade surface (4a) side. Instead, the tensile strength of the impeller (4) in the radially outward direction may be set smaller on the bottom surface (4b) side than on the blade surface (4a) side depending on the shape of the impeller (4).

In the above embodiment, a part of the impeller casing (3) is used as the shroud portion (3d). However, the present invention is not limited to this, and a casing shroud separate from the impeller casing (3) may be provided.

In the above embodiment, the impeller (4) is formed in a substantially truncated cone shape, but is not limited to this, and may be formed in, for example, a disk shape or the like.

In the above embodiment, the impeller (4) is rotationally driven by the electric motor (2). However, the present invention is not limited to this. For example, the impeller (4) is rotationally driven by an engine or a fluid pressure motor. You may do so.

In the above embodiment, the dynamic pressure gas bearings (14a, 2a) are used as the bearings of the drive shaft (21) of the electric motor (2).
Although 1a and 21b) are used, the invention is not limited to this, and for example, a simple gas bearing or a mechanical bearing may be used.

In the above embodiment, the present invention is applied to a turbo compressor as a centrifugal fluid machine. However, the present invention is not limited to this. For example, a centrifugal blower and a centrifugal fluid pump may be used as long as they have an open impeller. Etc. can be applied.

[0040]

As described above, according to the centrifugal fluid machine of the first aspect of the present invention, the flow loss caused by the gap between the impeller (4) and the casing shroud (3d) is reduced to operate the machine. Efficiency can be improved.

According to the second aspect of the present invention, the centrifugal fluid machine according to the first aspect of the present invention is specifically specified as a centrifugal compressor for compressing a fluid, and the compression efficiency of the centrifugal compressor is reduced. Improvement is achieved.

According to the third aspect of the present invention, when the impeller (4) is in a rotating state, the outer peripheral portion (4d) of the impeller (4) is surely deformed toward the casing shroud (3d). Thus, the effect of the invention described in claim 1 or 2 can be reliably obtained.

According to the fourth aspect of the present invention, by setting the inner diameter of the through hole (42) formed in the impeller (4), the tensile strength of the impeller (4) in the radially outward direction is set. The effect according to the third aspect of the invention can be easily and reliably obtained.

According to the fifth aspect of the present invention, with a configuration different from that of the third aspect, deformation of the outer peripheral portion (4d) during rotation of the impeller (4) is ensured. Side, so that the effect of the invention described in claim 2 can be reliably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a turbo compressor according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing setting of a gap amount between an impeller and a shroud portion.

FIG. 3 is a cross-sectional view showing deformation of an impeller due to centrifugal force.

FIG. 4 is an explanatory diagram showing the deformation properties of the impeller due to the gas pressure of the refrigerant gas.

FIG. 5 is a diagram corresponding to FIG. 1 in a conventional turbo compressor.

FIG. 6 is a diagram corresponding to FIG. 2 in a conventional turbo compressor.

[Explanation of symbols]

3d Shroud portion of impeller casing (casing shroud) 3e Suction passage 4 Impeller 4a Blade surface of impeller 4b Bottom surface of impeller (pressure receiving surface) 4d Outer peripheral portion of impeller 21 Drive shaft (drive shaft) of electric motor 32 Compression chamber 33 Discharge passage 34 Pressurizing chamber 41 Impeller blade 42 Impeller through hole H1 (r, z) Deformation amount at each part of impeller H2 + H3 + H4 + H5 Minimum required clearance X Rotation axis of impeller

Claims (5)

[Claims] 1. An impeller having a plurality of blades (41, 41,...) Radially arranged around a rotation axis (X) and for rotating and sending a fluid radially outward. (4), a suction passage (3e) opened on the rotation axis (X) to face the impeller (4), and a blade surface (4) of each blade (41) on the suction passage (3e) side.
a) a casing shroud (3d) disposed close to the opening of the suction passage (3e) from the opening of the suction passage (3e) to the outer peripheral side of the impeller (4), and the outer peripheral portion (4d) of the impeller (4). A centrifugal fluid machine, comprising: a discharge passage (33) that opens in opposition, wherein a fluid sucked from the suction passage (3e) is discharged from the discharge passage (33) by rotation of the impeller (4). The clearance between the casing shroud (3d) and the blade surface (4a) is set to a required minimum clearance amount (H2) set in advance for each radial portion of the blade surface (4a).
+ H3 + H4 + H5) plus the amount of deformation (H1 (r, z)) of the casing shroud (3d) for each of the radial portions generated when the impeller (4) rotates. A centrifugal fluid machine. 2. A compression chamber (32) according to claim 1, wherein the compression chamber (32) is disposed annularly around the outer periphery of the impeller (4), and compresses the fluid sucked from the suction passage (3e) by rotation of the impeller (4). A centrifugal fluid machine comprising: 3. The impeller (4) according to claim 1, wherein the radially outward tensile strength of the impeller (4) is opposite to that of the suction passage (3e) with respect to the rotation axis (X) direction. A centrifugal fluid machine configured to be small in size. 4. The impeller (4) according to claim 3, wherein a through hole (42) in which the drive shaft (21) is fitted is formed along the rotation axis (X). ), The inner diameter of which is set to be larger on the opposite side of the rotation axis (X) than the blade surface (4a) side. 5. The compression chamber (32) according to claim 2, wherein the impeller (4) is disposed on a side opposite to the blade surface (4a) of the impeller (4) in the direction of the rotation axis (X) and communicates with a compression chamber (32). 32) a pressurizing chamber (34) for applying the fluid pressure in the impeller (4) to the impeller (4), the impeller (4) being connected to the drive shaft (21) on the inner peripheral side thereof; The pressure receiving surface (4) of the impeller (4) facing the chamber (34)
b) is a pressurizing chamber (34) acting on the pressure receiving surface (4b).
The pressing force in the direction of the rotation axis (X) due to the fluid pressure in the inside is set to be larger than the pressing force in the direction of the rotation axis (X) due to the fluid pressure acting on the blade surface (4a). Centrifugal fluid machine.