JP7471976B2 - Fluid pump and fluid transfer device - Google Patents

Description

The present invention relates to a fluid pump and a fluid transfer device.

Patent document 1 (JP 2018-162865 A) describes a cryogenic fluid pump. The cryogenic fluid pump described in Patent document 1 has a shaft, a motor section, and a pump section.

The shaft has a first portion and a second portion extending from the first portion along the central axis of the shaft. The motor portion has a first housing, a motor stator, a first radial magnetic bearing, and a second radial magnetic bearing. The motor stator is disposed inside the first housing. When current is applied to the motor stator, the shaft is driven to rotate around the central axis. The first radial magnetic bearing and the second radial magnetic bearing are disposed to sandwich the motor stator from both sides in the central axis direction of the shaft, and rotatably support the first portion of the shaft.

The pump section has an impeller and a second housing. The impeller is attached to the tip of the shaft (the tip of the second part). A pump chamber in which the impeller is disposed is formed inside the second housing. The second housing has an inlet and an outlet that communicate with the pump chamber.

The cryogenic fluid pump described in Patent Document 1 is attached to a container so that the pump section is located inside the container. A cryogenic fluid such as liquid nitrogen is stored inside the container. As the shaft rotates, the impeller rotates inside the pump chamber. Centrifugal force caused by the rotation of the impeller causes the cryogenic fluid to flow into the pump chamber from the inlet and out of the outlet. The cryogenic fluid that flows out of the outlet is supplied to the object to be cooled through a distribution pipe that passes through the container and is connected to the outlet.

JP 2018-162865 A

As described above, in order to rotate the shaft, it is necessary to pass electricity through the motor stator. When electricity is passed through the motor stator, the motor stator generates heat. The heat generated in the motor stator is transferred to the pump section via the shaft, and increases the temperature of the cryogenic fluid stored inside the container. This causes a portion of the cryogenic fluid stored inside the container to vaporize. When the vaporized cryogenic fluid flows into the pump chamber, the pump efficiency decreases.

The present invention has been made in consideration of the problems with the conventional technology as described above. More specifically, the present invention provides a fluid pump that can prevent heat generated in the motor stator from being transmitted to the pump section.

A fluid pump according to one aspect of the present invention includes a rotating shaft, a motor section, and a pump section. The rotating shaft has a central axis, a first end that is an end in the central axis direction along the central axis, a second end that is an end opposite to the first end, a first shaft section extending from the first end to the second end, and a second shaft section extending from the first shaft section to the second end. The motor section includes a motor casing including an inner peripheral surface, a motor stator disposed inside the motor casing, a motor rotor disposed inside the motor casing so as to face the motor stator and constituted by a part of the first shaft section, a first radial magnetic bearing disposed inside the motor casing so as to be located closer to the first end side than the motor stator in the central axis direction, a second radial magnetic bearing disposed inside the motor casing so as to be located closer to the second end side than the motor stator in the central axis direction, and a cooling jacket including an outer peripheral surface and disposed between the motor casing and the motor stator in a radial direction perpendicular to the central axis direction so that the outer peripheral surface is in contact with the inner peripheral surface. The pump section has an impeller attached to the second end side of the second shaft section, and an impeller casing in which a pump chamber in which the impeller is housed is formed. The cooling jacket is disposed in a position at least partially overlapping with the motor stator in the central axial direction. The outer peripheral surface at a position overlapping with the motor stator in the central axial direction includes a first spiral groove formed in a spiral shape around the central axis. The width of the second radial magnetic bearing in the direction along the central axis is greater than the width of the first radial magnetic bearing in the direction along the central axis.

In the above fluid pump, the cooling jacket may have a third end which is an end in the central axis direction, and a fourth end which is an end opposite to the third end and is located farther from the first end than the third end. The cooling jacket may extend such that the fourth end reaches a position closer to the second end than the center in the central axis direction of the second radial magnetic bearing. The outer peripheral surface at a position overlapping with the second radial magnetic bearing in the central axis direction may include a second spiral groove formed in a spiral shape around the central axis.

In the above fluid pump, the outer peripheral surface may further include a first circumferential groove connected to the end of the first spiral groove on the third end side, a second circumferential groove located between the first spiral groove and the second spiral groove in the central axis direction and connected to the first spiral groove and the second spiral groove, and a third circumferential groove connected to the end of the second spiral groove on the fourth end side.

In the above fluid pump, the motor casing may be formed with a first refrigerant inlet communicating with the first circumferential groove, a refrigerant outlet communicating with the second circumferential groove, and a second refrigerant inlet communicating with the third circumferential groove.

In the above fluid pump, the motor casing may be formed with a first refrigerant outlet communicating with the first circumferential groove, a refrigerant inlet communicating with the second circumferential groove, and a second refrigerant outlet communicating with the third circumferential groove.

A fluid transfer device according to one aspect of the present invention includes a container and the above-described fluid pump attached to the container such that the pump portion is located inside the container.

In the fluid pump according to one aspect of the present invention, the motor stator can be cooled by flowing a coolant through a flow path defined by a first spiral groove formed on the outer peripheral surface of the cooling jacket and the inner peripheral surface of the motor casing. In addition, in the fluid pump according to one aspect of the present invention, the width in the central axial direction of the second radial magnetic bearing is larger than the width in the central axial direction of the first radial bearing, so that a relatively large distance can be ensured between the motor stator and the pump section. Therefore, with the fluid pump according to one aspect of the present invention, the heat generated in the motor stator can be prevented from being transmitted to the pump section.

1 is a cross-sectional view of a fluid pump 10. FIG. 2 is a side view of the cooling jacket 27 of the fluid pump 10. FIG. FIG. 2 is a front view of the fluid transfer device 100. 1 is a cross-sectional view of a fluid transfer device 100. FIG. 2 is a cross-sectional view of the fluid pump 10A. FIG. 2 is a side view of a cooling jacket 27 in the fluid pump 10A. FIG. FIG. 2 is a cross-sectional view of the fluid pump 10B.

Details of the embodiment will be explained with reference to the drawings. In the following drawings, the same or corresponding parts will be given the same reference symbols, and duplicate explanations will not be repeated.

First Embodiment
The configuration of a fluid pump according to a first embodiment (hereinafter referred to as a "fluid pump 10") will be described below.

Figure 1 is a cross-sectional view of a fluid pump 10. As shown in Figure 1, the fluid pump 10 has a rotating shaft 1, a motor section 2, and a pump section 3.

<Detailed configuration of rotating shaft 1>
1, the rotating shaft 1 has a central axis A. The rotating shaft 1 has a first end 1a and a second end 1b in a direction along the central axis A (hereinafter referred to as the "central axis direction"). The second end 1b is the end opposite to the first end 1a.

The rotating shaft 1 has a first shaft portion 11 and a second shaft portion 12. The first shaft portion 11 extends from the first end 1a toward the second end 1b. The second shaft portion 12 extends from the first shaft portion 11 toward the second end 1b. It is preferable that the diameter of the first shaft portion 11 is larger than the diameter of the second shaft portion 12.

<Detailed configuration of motor unit 2>
As shown in FIG. 1, the motor section 2 has a motor casing 21 , a motor stator 22 , a motor rotor 23 , a radial magnetic bearing 24 , a radial magnetic bearing 25 , a thrust magnetic bearing 26 , and a cooling jacket 27 .

The first shaft portion 11 is housed in the motor casing 21. From another perspective, the first shaft portion 11 is the portion of the rotating shaft 1 housed in the motor casing 21. The motor casing 21 has a cylindrical shape with a bottom. The motor casing 21 has a first casing 21a, a second casing 21b, and a casing cover 21c. The motor casing 21 has an inner circumferential surface 21d.

The first casing 21a has a cylindrical shape. The first casing 21a extends along the central axis direction. The second casing 21b has a cylindrical shape. The second casing 21b extends along the central axis direction. The second casing 21b is connected to the upper end of the first casing 21a. The connection between the first casing 21a and the second casing 21b is made by, for example, bolts and nuts. The casing lid 21c has a flat plate shape. The casing lid 21c is attached to the upper end of the second casing 21b. This closes the upper end of the second casing 21b.

The motor casing 21 has a refrigerant inlet 21e and a refrigerant outlet 21f. The refrigerant inlet 21e is connected to a circumferential groove 27cc, which will be described later, and the refrigerant outlet 21f is connected to a circumferential groove 27cb, which will be described later. The refrigerant is introduced from the refrigerant inlet 21e and discharged from the refrigerant outlet 21f. The refrigerant is, for example, water.

The motor stator 22 is disposed inside the motor casing 21. More specifically, the motor stator 22 is disposed inside the first casing 21a. The motor stator 22 is configured by winding a stator coil around a stator core.

The motor rotor 23 is, for example, a part of the first shaft portion 11. The motor rotor 23 is formed of a permanent magnet. The motor rotor 23 is arranged to face the motor stator 22 in a direction (hereinafter referred to as the "radial direction") that passes through the central axis A and is perpendicular to the central axis direction. From another perspective, the motor stator 22 is arranged around the motor rotor 23. The direction of the magnetic field generated by the motor stator 22 is sequentially switched by sequentially switching the direction of the current flowing through the stator coil by an inverter circuit (not shown) or the like. This generates a driving force for the motor rotor 23, and the rotating shaft 1 rotates around the central axis A. Note that the motor rotor 23 generates heat when a current flows through the stator coil (i.e., when the motor unit 2 rotates the rotating shaft 1).

The radial magnetic bearing 24 is disposed inside the motor casing 21 (more specifically, the first casing 21a). The radial magnetic bearing 24 supports the rotating shaft 1 (more specifically, the first shaft portion 11) so that it can rotate around the central axis A. The radial magnetic bearing 24 supports the radial load (radial load) applied to the rotating shaft 1.

The radial magnetic bearing 25 is disposed inside the motor casing 21 (more specifically, the first casing 21a). The radial magnetic bearing 25 supports the rotating shaft 1 (more specifically, the first shaft portion 11) so that it can rotate around the central axis A. The radial magnetic bearing 25 supports the radial load (radial load) applied to the rotating shaft 1.

The radial magnetic bearing 24 is disposed closer to the first end 1a than the motor stator 22 in the central axis direction. The radial magnetic bearing 25 is disposed closer to the second end 1b than the motor stator 22 in the central axis direction. In other words, the radial magnetic bearing 24 and the radial magnetic bearing 25 are disposed so as to sandwich the motor stator 22 in the central axis direction.

The radial magnetic bearing 24 has a width W1 in the central axis direction. The radial magnetic bearing 25 has a width W2 in the central axis direction. Width W2 is greater than width W1.

The thrust magnetic bearing 26 is disposed inside the motor casing 21. The thrust magnetic bearing 26 supports the load in the thrust direction (load in the central axis direction) applied to the rotating shaft 1. Note that the radial magnetic bearing 24, the radial magnetic bearing 25, and the thrust magnetic bearing 26 use magnetic levitation by electromagnetic force, and therefore support the rotating shaft 1 without contact.

The cooling jacket 27 has a cylindrical shape. The cooling jacket 27 extends along the central axis direction. The cooling jacket 27 has a third end 27a and a fourth end 27b in the central axis direction. The fourth end 27b is the end opposite to the third end 27a. The fourth end 27b is located farther from the first end 1a than the third end 27a. The cooling jacket 27 is arranged at a position overlapping the motor stator 22 in the central axis direction. From another perspective, the third end 27a is located closer to the first end 1a than the end on the second end 1b side of the motor stator 22, and the fourth end 27b is located farther from the first end 1a than the end on the first end 1a side of the motor stator 22. Preferably, the third end 27a is located closer to the first end 1a than the center in the central axis direction of the motor stator 22, and the fourth end 27b reaches the end on the second end 1b side of the motor stator 22.

The cooling jacket 27 has an outer peripheral surface 27c. The cooling jacket 27 is disposed radially between the motor casing 21 and the motor stator 22 so that the outer peripheral surface 27c is in contact with the inner peripheral surface 21d.

2 is a side view of the cooling jacket 27 in the fluid pump 10. As shown in FIG. 1 and FIG. 2, the outer peripheral surface 27c, which is located at a position overlapping with the motor stator 22 in the central axis direction, is formed with a spiral groove 27ca, a circumferential groove 27cb, and a circumferential groove 27cc. The spiral groove 27ca is a groove formed in a spiral shape around the central axis A. The circumferential groove 27cb and the circumferential groove 27cc are grooves formed in a circumferential shape around the central axis A. From another perspective, in a side view perpendicular to the central axis direction, the extension direction of the spiral groove 27ca is inclined with respect to the central axis direction, and the extension direction of the circumferential groove 27cb and the circumferential groove 27cc is perpendicular to the central axis. The outer peripheral surface 27c is recessed at the spiral groove 27ca, the circumferential groove 27cb, and the circumferential groove 27cc.

The circumferential groove 27cb is connected to the end of the spiral groove 27ca on the third end 27a side. The circumferential groove 27cc is connected to the end of the spiral groove 27ca on the fourth end 27b side.

As described above, outer peripheral surface 27c is in contact with inner peripheral surface 21d, so that a flow path is formed by spiral groove 27ca, circumferential groove 27cb, and circumferential groove 27cc and inner peripheral surface 21d. As described above, refrigerant inlet 21e is connected to circumferential groove 27cc, and refrigerant outlet 21f is connected to circumferential groove 27cb, so that the refrigerant introduced from refrigerant inlet 21e flows through the above flow path and is discharged from refrigerant outlet 21f.

<Detailed configuration of pump section 3>
As shown in FIG. 1 , the pump section 3 has an impeller 31 , an impeller casing 32 , and a shaft cover 33 .

The impeller 31 is attached to the rotating shaft 1. More specifically, the impeller 31 is attached to the tip of the second shaft portion 12 (the end of the second shaft portion 12 opposite the first shaft portion 11).

The impeller casing 32 has an upper surface 32a, a bottom surface 32b, an insertion hole 32c, a pump chamber 32d, an intake port 32e, a discharge port 32f, and a flow path 32g.

The top surface 32a is the surface facing the motor unit 2. The bottom surface 32b is the opposite surface of the top surface 32a. The insertion hole 32c penetrates the impeller casing 32 along the direction from the top surface 32a to the bottom surface 32b. The rotating shaft 1 (second shaft portion 12) is inserted into the insertion hole 32c. The pump chamber 32d is formed inside the impeller casing 32. The pump chamber 32d is an internal space of the impeller casing 32 in which the impeller 31 is housed. The pump chamber 32d is connected to the insertion hole 32c inside the impeller casing 32. The portion of the insertion hole 32c that is closer to the top surface 32a than the pump chamber 32d is called the first portion 32ca, and the portion of the insertion hole 32c that is closer to the bottom surface 32b than the pump chamber 32d is called the second portion 32cb. The gap between the inner wall surface of the first portion 32ca and the outer circumferential surface of the rotating shaft 1 (second shaft portion 12) is liquid-tightly sealed.

The suction port 32e is connected to the pump chamber 32d via the second portion 32cb. The discharge port 32f is connected to the pump chamber 32d via a flow path 32g formed inside the impeller casing 32. As the rotating shaft 1 rotates, the impeller 31 rotates in the pump chamber 32d. Fluid is sucked from the suction port 32e into the pump chamber 32d by the centrifugal force caused by the rotation of the impeller 31, and is discharged from the pump chamber 32d to the discharge port 32f.

The shaft cover 33 covers the rotating shaft 1 between the impeller casing 32 and the motor section 2. One end of the shaft cover 33 is connected to the upper surface 32a, and the other end is connected to the motor casing 21. This integrates the motor section 2 and the pump section 3. The shaft cover 33 and the impeller casing 32 may be formed as a single unit.

<Fluid Transfer Device Using Fluid Pump 10>
The configuration of a fluid transfer device using the fluid pump 10 (hereinafter referred to as "fluid transfer device 100") will be described below.

Figure 3 is a front view of the fluid transfer device 100. Figure 4 is a cross-sectional view of the fluid transfer device 100. As shown in Figures 3 and 4, the fluid transfer device 100 has a fluid pump 10, a container 20, a conduit 30, and a conduit 40.

The container 20 is, for example, a vacuum container. The container 20 has a container body 20a and a pressure wall 20b. The container body 20a has an opening at the upper end. The pressure wall 20b is attached to the upper end of the container body 20a to close the opening of the container body 20a and to define the internal space of the container 20. A fluid is stored inside the container 20. The fluid stored inside the container 20 is, for example, a low-temperature fluid such as liquid nitrogen.

The fluid pump 10 is attached to the container 20 such that the pump section 3 is located inside the container 20. More specifically, the fluid pump 10 is attached to the container 20 by fixing the motor section 2 (motor casing 21) onto the pressure wall 20b.

The pipe 30 penetrates the pressure wall 20b so that one end is located inside the vessel 20. Although not shown, the other end of the pipe 30 is connected to a source of cryogenic fluid. That is, the cryogenic fluid is supplied to the inside of the vessel 20 via the pipe 30. The pipe 40 penetrates the pressure wall 20b so that one end is connected to the discharge port 32f. The other end of the pipe 40 is connected to an object to be cooled, such as a superconducting cable.

Rotating the rotating shaft 1 rotates the impeller 31. The centrifugal force generated by the rotation of the impeller 31 causes the low-temperature fluid stored inside the container 20 to be sucked in through the suction port 32e and discharged through the discharge port 32f. The low-temperature fluid discharged from the discharge port 32f is supplied to the object to be cooled via the pipeline 40. In this way, the fluid transfer device 100 transfers the low-temperature fluid from the low-temperature fluid supply source through the container 20 to the object to be cooled.

<Effects of the Fluid Pump 10>
The effects of the fluid pump 10 will be described below.

In the fluid pump 10, the motor stator 22 can be cooled by flowing the refrigerant through a flow path defined by the spiral groove 27ca formed on the outer peripheral surface 27c and the inner peripheral surface 21d. In addition, in the fluid pump 10, the width W2 is larger than the width W1, so that the distance between the motor stator 22 and the pump section 3 can be relatively large. Therefore, the fluid pump 10 can suppress the heat generated in the motor stator 22 from being transmitted to the pump section 3. As a result, it is possible to suppress the decrease in pump efficiency caused by the vaporization of the low-temperature fluid stored inside the container 20 and the flow of the vaporized low-temperature fluid into the pump chamber 32d.

In the fluid pump 10, the circumferential grooves 27cb and 27cc are formed on the outer circumferential surface 27c, so that even if the cooling jacket 27 is attached to the motor casing 21 while rotating around the central axis A, the refrigerant inlet 21e and the refrigerant outlet 21f can be connected to the circumferential grooves 27cc and 27cb, respectively.

Second Embodiment
The configuration of a fluid pump according to the second embodiment (hereinafter referred to as "fluid pump 10A") will be described below. Here, differences from the configuration of fluid pump 10 will be mainly described, and overlapping descriptions will not be repeated.

Figure 5 is a cross-sectional view of the fluid pump 10A. As shown in Figure 5, the fluid pump 10A has a rotating shaft 1, a motor section 2, and a pump section 3. The rotating shaft 1 has a central axis A, a first end 1a, a second end 1b, a first shaft section 11, and a second shaft section 12. The motor section 2 has a motor casing 21, a motor stator 22, a motor rotor 23, a radial magnetic bearing 24, a radial magnetic bearing 25, a thrust magnetic bearing 26, and a cooling jacket 27. The pump section 3 has an impeller 31, an impeller casing 32, and a shaft cover 33. In these respects, the configuration of the fluid pump 10A is common to the configuration of the fluid pump 10. In the fluid pump 10A, the width W2 is preferably larger than the width W1, but may be equal to the width W1 or smaller than the width W1.

The configuration of the fluid pump 10A differs from the configuration of the fluid pump 10 with respect to the details of the cooling jacket 27 and the details of the motor casing 21. These points are explained in detail below.

<Detailed configuration of cooling jacket 27>
The cooling jacket 27 is disposed at a position overlapping with the motor stator 22 and the radial magnetic bearing 25 in the central axial direction. More specifically, the fourth end 27b of the cooling jacket 27 extends to a position closer to the second end 1b than to the center in the central axial direction of the radial magnetic bearing 25. The cooling jacket 27 at a position overlapping with the radial magnetic bearing 25 in the central axial direction is located between the radial magnetic bearing and the motor casing 21 in the radial direction.

Figure 6 is a side view of the cooling jacket 27 in the fluid pump 10A. As shown in Figures 5 and 6, the outer peripheral surface 27c, which is located at a position overlapping with the radial magnetic bearing 25 in the central axis direction, is formed with a spiral groove 27cd and a circumferential groove 27ce. In the cooling jacket 27 in the fluid pump 10A, the circumferential groove 27cc is located between the spiral groove 27ca and the spiral groove 27cd in the central axis direction, and is connected to the end of the spiral groove 27ca on the fourth end 27b side and the end of the spiral groove 27cd on the third end 27a side.

The spiral groove 27cd is a groove formed in a spiral shape around the central axis A. The circumferential groove 27ce is a groove formed in a circumferential shape around the central axis A. From another perspective, in a side view perpendicular to the central axis direction, the extension direction of the spiral groove 27cd is inclined with respect to the central axis direction, and the extension direction of the circumferential groove 27ce is perpendicular to the central axis. The outer peripheral surface 27c is recessed at the spiral groove 27cd and the circumferential groove 27ce. The circumferential groove 27ce is connected to the end of the spiral groove 27cd on the fourth end 27b side.

<Detailed Configuration of Motor Casing 21>
The motor casing 21 further has a refrigerant inlet 21g. The refrigerant inlet 21g is connected to the circumferential groove 27ce. In the fluid pump 10A, the refrigerant inlet 21e is connected to the circumferential groove 27cb, and the refrigerant outlet 21f is connected to the circumferential groove 27cc. The refrigerant is introduced from the refrigerant inlet 21e and the refrigerant inlet 21g. A flow path is formed by the spiral groove 27ca, the circumferential groove 27cb, the circumferential groove 27cc, the spiral groove 27cd, the circumferential groove 27ce, and the inner circumferential surface 21d. Since the refrigerant outlet 21f is connected to the circumferential groove 27cc, the refrigerant introduced from the refrigerant inlet 21e and the refrigerant inlet 21g flows through the above flow path and is discharged from the refrigerant outlet 21f.

<Effects of Fluid Pump 10A>
The effects of the fluid pump 10A will be described below. Here, differences from the effects of the fluid pump 10 will be mainly described, and overlapping descriptions will not be repeated.

In the fluid pump 10A, the radial magnetic bearing 25 can be cooled by flowing a refrigerant through a flow path defined by the spiral groove 27cd formed on the outer peripheral surface 27c and the inner peripheral surface 21d, so that the heat generated in the radial magnetic bearing 25 can be prevented from being transmitted to the pump section 3.

Since a low-temperature fluid is stored inside the container 20, the temperature of the motor casing 21 located near the portion fixed to the pressure wall 20b is low, and there is a risk of condensation occurring on the outer circumferential surface of the motor casing 21 located near that portion. In the fluid pump 10A, by flowing a refrigerant through a flow path defined by the spiral groove 27cd formed on the outer circumferential surface 27c and the inner circumferential surface 21d, it is possible to cool the radial magnetic bearing 25 while warming the motor casing 21 located near the portion fixed to the pressure wall 20b, thereby suppressing the occurrence of condensation as described above.

In the fluid pump 10A, the outer peripheral surface 27c is formed with the circumferential grooves 27cc, 27cb, and 27ce, so that even if the cooling jacket 27 is attached to the motor casing 21 while rotating around the central axis A, the refrigerant inlet 21e, the refrigerant outlet 21f, and the refrigerant inlet 21g can be connected to the circumferential grooves 27cc, 27cb, and 27ce, respectively.

In the fluid pump 10A, the motor casing 21 has a refrigerant inlet 21e, a refrigerant outlet 21f, and a refrigerant inlet 21g, so that the flow path for cooling the motor stator 22 and the flow path for cooling the radial magnetic bearing 25 can be shortened. As a result, it is possible to use a pump with a low discharge pressure to supply the refrigerant, and the device configuration can be simplified.

<Modification>
A modified example of the fluid pump 10A (hereinafter referred to as "fluid pump 10B") will be described below.

Figure 7 is a cross-sectional view of fluid pump 10B. As shown in Figure 7, motor casing 21 has refrigerant inlet 21h, refrigerant outlet 21i, and refrigerant outlet 21j. Refrigerant inlet 21h is connected to circumferential groove 27cc, and refrigerant outlet 21i and refrigerant outlet 21j are connected to circumferential groove 27cb and circumferential groove 27ce, respectively. Fluid pump 10B having such a configuration also achieves the same effects as fluid pump 10A.

Although the embodiment of the present invention has been described above, the above-mentioned embodiment can be modified in various ways. Furthermore, the scope of the present invention is not limited to the above-mentioned embodiment. The scope of the present invention is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

The above embodiment is particularly advantageously applicable to fluid pumps and fluid transfer devices used for cryogenic fluids such as liquid nitrogen.

1 Rotating shaft, 1a first end, 1b second end, 11 first shaft portion, 12 second shaft portion, 2 motor portion, 21 motor casing, 21a first casing, 21b second casing, 21c casing cover, 21d inner circumferential surface, 21e refrigerant inlet, 21f refrigerant outlet, 21g refrigerant inlet, 21h refrigerant inlet, 21i, 21j refrigerant outlet, 22 motor stator, 23 motor rotor, 24, 25 radial magnetic bearing, 26 thrust magnetic bearing, 27 cooling jacket, 27a third end, 27b fourth end, 27c outer circumferential surface, 27ca spiral groove, 27cb, 27cc circumferential groove, 27cd spiral groove, 27ce circumferential groove, 3 pump portion, 31 impeller, 32 impeller casing, 32a upper surface, 32b Bottom surface, 32c insertion hole, 32ca first part, 32cb second part, 32d pump chamber, 32e suction port, 32f discharge port, 32g flow path, 33 shaft cover, 10, 10A, 10B fluid pump, 20 container, 20a container body, 20b pressure wall, 30, 40 pipeline, 100 fluid transfer device, A central axis, W1, W2 width.

Claims (4)

a rotating shaft having a central axis, a first end which is an end in a central axis direction along the central axis, a second end which is an end opposite to the first end, a first shaft portion extending from the first end toward the second end, and a second shaft portion extending from the first shaft portion toward the second end;
a motor section including: a motor casing including an inner circumferential surface; a motor stator disposed inside the motor casing; a motor rotor disposed inside the motor casing so as to face the motor stator and constituted by a part of the first shaft portion; a first radial magnetic bearing disposed inside the motor casing so as to be located closer to the first end than the motor stator in the central axis direction; a second radial magnetic bearing disposed inside the motor casing so as to be located closer to the second end than the motor stator in the central axis direction; and a cooling jacket including an outer circumferential surface and disposed between the motor casing and the motor stator in a radial direction perpendicular to the central axis direction so that the outer circumferential surface is in contact with the inner circumferential surface;
a pump section including an impeller attached to the second end side of the second shaft section and an impeller casing having a pump chamber formed therein in which the impeller is housed,
the cooling jacket is disposed at a position at least partially overlapping with the motor stator in the central axial direction,
the outer circumferential surface at a position overlapping with the motor stator in the central axis direction includes a first spiral groove formed in a spiral shape around the central axis,
a width of the second radial magnetic bearing in a direction along the central axis is larger than a width of the first radial magnetic bearing in a direction along the central axis,
the cooling jacket has a third end which is an end in the central axis direction, and a fourth end which is an end opposite to the third end and is located farther from the first end than the third end,
the cooling jacket extends such that the fourth end reaches a position closer to the second end than a center of the second radial magnetic bearing in the central axial direction,
the outer circumferential surface at a position overlapping with the second radial magnetic bearing in the central axis direction includes a second helical groove formed in a spiral shape around the central axis,
the outer peripheral surface further includes a first circumferential groove connected to an end of the first spiral groove on the third end side, a second circumferential groove located between the first spiral groove and the second spiral groove in the central axis direction and connected to the first spiral groove and the second spiral groove, and a third circumferential groove connected to an end of the second spiral groove on the fourth end side. 2. The fluid pump according to claim 1, wherein the motor casing is formed with a first refrigerant inlet communicating with the first circumferential groove, a refrigerant outlet communicating with the second circumferential groove, and a second refrigerant inlet communicating with the third circumferential groove. 2. The fluid pump according to claim 1, wherein the motor casing is formed with a first refrigerant outlet communicating with the first circumferential groove, a refrigerant inlet communicating with the second circumferential groove, and a second refrigerant outlet communicating with the third circumferential groove. A container;
A fluid transfer device comprising: the fluid pump according to any one of claims 1 to 3 , attached to the container so that the pump portion is located inside the container.

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