JP2018013040A - Bearing assembly and pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing assembly having a structure in which a gap between a rotary side bearing and a stationary side bearing is not clogged with a foreign body.SOLUTION: A bearing assembly 10 comprises: a stationary side bearing 12 including a cylindrical stationary side radial surface 12a, and a stationary side thrust surface 12b located radially outside the stationary side radial surface 12a; a rotary side bearing 11 including a cylindrical rotary side radial surface 11a surrounding the stationary side radial surface 12a, and a rotary side thrust surface 11b located radially outside the rotary side radial surface 11a; and an intermediate bearing 17 arranged between the rotary side thrust surface 11b and the stationary side thrust surface 12b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a bearing assembly and a pump device including the bearing assembly.

  Since the canned motor pump in which the motor and the pump are integrally formed does not require a shaft seal device for sealing the gap between the rotating shaft and the pump casing, liquid leakage does not occur. Therefore, the canned motor pump is widely used in the field where liquid leakage is disliked. Furthermore, a canned motor pump equipped with an axial gap type PM motor that does not occupy a space is preferably used in the field of downsizing the entire apparatus such as a semiconductor manufacturing apparatus.

  FIG. 7 is a sectional view showing a motor pump. The motor pump shown in FIG. 7 is a canned motor pump equipped with an axial gap type PM motor. As shown in FIG. 7, the motor pump includes an impeller 101 in which a plurality of permanent magnets 105 are embedded, a motor stator 106 that generates magnetic force acting on these permanent magnets 105, and a pump that houses the impeller 101. A casing 102, a motor casing 103 that houses the motor stator 106, and a bearing assembly 110 that supports the radial load and the thrust load of the impeller 101 are provided. The motor stator 106 and the bearing assembly 110 are arranged on the suction side of the impeller 101.

  The impeller 101 is rotatably supported by a single bearing assembly 110. The bearing assembly 110 is a sliding bearing (dynamic pressure bearing) that uses the dynamic pressure of liquid. The bearing assembly 110 is composed of a combination of a rotating side bearing 111 and a fixed side bearing 112 that are gently engaged with each other. The rotation-side bearing 111 is fixed to the impeller 101, and the fixed-side bearing 112 is fixed to the motor casing 103.

  A part of the liquid discharged from the impeller 101 is guided to the bearing assembly 110 through a minute gap between the impeller 101 and the motor casing 103. When the rotation-side bearing 111 rotates together with the impeller 101, a fluid dynamic pressure is generated between the rotation-side bearing 111 and the fixed-side bearing 112, whereby the impeller 101 is supported in a non-contact manner by the bearing assembly 110. .

  When the motor pump is operated for a long period of time, the bearing assembly 110, which is a plain bearing, is worn. In this case, the bearing assembly 110 needs to be periodically replaced. Therefore, silicon carbide (SiC) having high hardness and low wear may be employed as the bearing assembly 110.

JP 2001-65487 A

  The liquid guided to the bearing assembly 110 may contain foreign matter, and this foreign matter may be clogged between the rotation-side bearing 111 and the fixed-side bearing 112. However, since a magnetic force is always generated between the permanent magnet 105 and the motor stator 106 (that is, when the motor pump is operated and stopped), the rotation-side bearing 111 and the fixed-side bearing 112 are not connected. At all times, a pulling force acts. Therefore, once foreign matter is clogged between the rotation-side bearing 111 and the fixed-side bearing 112 during the operation of the motor pump, even if the motor pump is stopped, it acts between the rotation-side bearing 111 and the fixed-side bearing 112. The foreign matter may not be removed by the force applied. As a result, there is a possibility that the motor pump cannot be driven again.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a bearing assembly having a structure in which foreign matter is not clogged in a gap between a rotary side bearing and a fixed side bearing. Moreover, an object of this invention is to provide the pump apparatus provided with such a bearing assembly.

  In order to achieve the above-described object, one aspect of the present invention includes a fixed-side bearing having a cylindrical fixed-side radial surface, and a fixed-side thrust surface positioned radially outward of the fixed-side radial surface, and the fixed A rotation-side bearing having a cylindrical rotation-side radial surface surrounding the side-radial surface, and a rotation-side thrust surface positioned radially outward of the rotation-side radial surface; and the rotation-side thrust surface and the fixed-side thrust surface A bearing assembly comprising an intermediate bearing disposed therebetween.

The preferable aspect of this invention is further equipped with the stopper which has the stopper end surface protruded outside from the said fixed side radial surface, The said intermediate bearing is arrange | positioned around the said stopper, It is characterized by the above-mentioned.
In a preferred aspect of the present invention, the intermediate bearing has a first bearing end surface that contacts the fixed-side thrust surface and a second bearing end surface that contacts the rotating-side thrust surface. The distance from the bearing end surface to the second bearing end surface is greater than the distance from the fixed thrust surface to the stopper end surface of the stopper.
In a preferred aspect of the present invention, the stopper is configured integrally with the fixed-side bearing.
In a preferred aspect of the present invention, the stopper is composed of a member different from the fixed side bearing.

In a preferred aspect of the present invention, the intermediate bearing is made of a softer material than the fixed side bearing and the rotary side bearing.
In a preferred aspect of the present invention, the fixed side bearing and the rotary side bearing are made of ceramic, and the intermediate bearing is made of resin.
In a preferred aspect of the present invention, the intermediate bearing is rotatably disposed between the rotation-side thrust surface and the fixed-side thrust surface, and the intermediate bearing is capable of sliding contact with the fixed-side thrust surface. It has the 1st bearing end surface and the 2nd bearing end surface which can be in sliding contact with the said rotation side thrust surface, It is characterized by the above-mentioned.

  Another aspect of the present invention includes an impeller embedded with a permanent magnet, a pump casing that houses the impeller, a motor stator having a plurality of stator coils, and a motor casing that houses the motor stator. And the bearing assembly for supporting the impeller, wherein the rotation side bearing of the bearing assembly is fixed to the impeller, and the fixed side bearing of the bearing assembly is fixed to the motor casing. This is a pump device.

In a preferred aspect of the present invention, the bearing assembly is the bearing assembly shown in the preferred aspect, and a first axial clearance is formed between the rotation-side bearing and the stopper. A second axial gap is formed between the impeller and the motor casing, and the first axial gap is smaller than the second axial gap.
A preferred aspect of the present invention further includes an inverter device that supplies current to the motor stator, wherein the inverter device contacts the stopper and the current supplied to the motor stator is predetermined. When the threshold value is exceeded, the supply of current to the motor stator is stopped.

  The bearing assembly includes an intermediate bearing disposed between the rotation-side thrust surface of the rotation-side bearing and the fixed-side thrust surface of the fixed-side bearing. Therefore, foreign matter that has entered the bearing assembly may be clogged in the gap between the rotation-side bearing and the intermediate bearing and / or the gap between the fixed-side bearing and the intermediate bearing. There is no clogging between the bearings.

It is sectional drawing which shows the pump apparatus which concerns on one Embodiment of this invention. It is a figure which shows a bearing assembly. It is an enlarged view of an intermediate bearing and a stopper. It is the figure which looked at the intermediate bearing from the axial direction. It is a figure which shows the rotation side bearing which contacts a stopper. It is a figure which shows other embodiment of a bearing assembly. It is sectional drawing which shows a motor pump.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a pump device according to an embodiment of the present invention. This pump device includes a motor pump in which a motor and a pump are integrally formed. The motor pump shown in FIG. 1 is a canned motor pump equipped with an axial gap type PM motor. As shown in FIG. 1, the motor pump includes an impeller 1 in which a plurality of permanent magnets 5 are embedded, a motor stator 6 that generates magnetic force acting on these permanent magnets 5, and a pump that houses the impeller 1. A casing 2, a motor casing 3 that houses the motor stator 6, and a bearing assembly 10 that supports a radial load and a thrust load of the impeller 1 are provided.

  The motor stator 6 and the bearing assembly 10 are disposed on the suction side of the impeller 1. In the present embodiment, a plurality of permanent magnets 5 are provided, but the present invention is not limited to this embodiment, and a single permanent magnet with a plurality of magnetic poles magnetized may be used. Specifically, one annular permanent magnet having a plurality of magnetic poles in which S poles and N poles are alternately magnetized may be used.

  An O-ring 9 as a seal member is provided between the pump casing 2 and the motor casing 3. By providing the O-ring 9, it is possible to prevent liquid from leaking between the pump casing 2 and the motor casing 3.

  A suction port 15 having a suction port 15 a is connected to the motor casing 3. The suction port 15 has a flange shape and is connected to a suction line (not shown). Liquid passages 15b, 3a, and 10a are formed in the central portions of the suction port 15, the motor casing 3, and the bearing assembly 10, respectively. These liquid flow paths 15b, 3a, and 10a are connected in a line and constitute one liquid flow path that extends from the suction port 15a to the liquid inlet of the impeller 1. The liquid flow paths 15b, 3a, 10a communicate with the liquid inlet of the impeller 1.

  The motor pump according to the present embodiment is a canned motor pump equipped with an axial gap type PM motor in which the permanent magnet 5 and the motor stator 6 are disposed along the liquid flow paths 15b, 3a, and 10a.

  A discharge port 16 having a discharge port 16a is provided on the side surface of the pump casing 2, and the liquid pressurized by the rotating impeller 1 is discharged through the discharge port 16a. The motor pump according to the present embodiment is a so-called end-top type motor pump in which the suction port 15a and the discharge port 16a are orthogonal to each other.

  The impeller 1 is formed of a nonmagnetic material that is slippery and difficult to wear. For example, resins such as PTFE (polytetrafluoroethylene) and PPS (polyphenylene sulfide), and ceramics are preferably used. The pump casing 2 and the motor casing 3 can also be formed from the same material as the impeller 1.

  FIG. 2 is a view showing the bearing assembly 10. The impeller 1 is rotatably supported by a single bearing assembly 10. The bearing assembly 10 is a sliding bearing (dynamic pressure bearing) that uses the dynamic pressure of liquid. The bearing assembly 10 includes a fixed-side bearing 12, a rotation-side bearing 11 disposed around the fixed-side bearing 12, and an intermediate bearing disposed rotatably between the fixed-side bearing 12 and the rotation-side bearing 11. 17.

  The fixed-side bearing 12 has a cylindrical fixed-side radial surface 12a and a fixed-side thrust surface 12b located on the radially outer side of the fixed-side radial surface 12a. The rotation-side bearing 11 has a cylindrical rotation-side radial surface 11a that surrounds the fixed-side radial surface 12a, and a rotation-side thrust surface 11b that is located radially outward of the rotation-side radial surface 11a. The rotation side bearing 11 is arranged so as to surround the fixed side bearing 12. The intermediate bearing 17 is disposed between the rotation-side thrust surface 11 b of the rotation-side bearing 11 and the fixed-side thrust surface 12 b of the fixed-side bearing 12.

  The rotation-side bearing 11 is fixed to the impeller 1 and is disposed so as to surround the liquid inlet of the impeller 1. The fixed side bearing 12 is fixed to the motor casing 3 and is arranged on the suction side of the rotation side bearing 11.

  The rotation-side radial surface 11a and the fixed-side radial surface 12a are radial surfaces that support the radial load of the impeller 1, and the rotation-side thrust surface 11b and the fixed-side thrust surface 12b are thrust surfaces that support the thrust load of the impeller 1. is there. The rotation-side radial surface 11 a and the fixed-side radial surface 12 a are parallel to the axis of the impeller 1, and the rotation-side thrust surface 11 b and the fixed-side thrust surface 12 b are perpendicular to the axis of the impeller 1. The rotation-side radial surface 11a and the rotation-side thrust surface 11b are perpendicular to each other, and the fixed-side radial surface 12a and the fixed-side thrust surface 12b are perpendicular to each other. In addition, the shape of the rotation side bearing 11 and the shape of the fixed side bearing 12 are not limited to the example of FIG. 2, and the rotation side bearing 11 and the fixed side bearing 12 may have a taper surface.

  As shown in FIG. 2, the bearing assembly 10 further includes a stopper 19 having a stopper end surface 19b that protrudes outward from the fixed-side radial surface 12a. The stopper 19 is disposed between the rotation side thrust surface 11b and the fixed side thrust surface 12b. The fixed radial surface 12 a and the fixed thrust surface 12 b are connected to each other via a stopper 19.

  The stopper 19 may have an annular shape, or may be composed of a plurality of members arranged at equal intervals along the circumferential direction of the fixed-side radial surface 12a. In the present embodiment, the stopper 19 is configured integrally with the fixed-side bearing 12.

  The intermediate bearing 17 has an annular shape, and includes a first bearing end surface 17 a that contacts the fixed thrust surface 12 b of the fixed bearing 12 and a second contact that contacts the rotating thrust surface 11 b of the rotating bearing 11. It has a bearing end surface 17b and an inner surface 17c that connects the first bearing end surface 17a and the second bearing end surface 17b. The rotation side bearing 11, the fixed side bearing 12, and the intermediate bearing 17 are arranged concentrically with each other.

  The intermediate bearing 17 is disposed around the stopper 19. More specifically, the inner surface 17 c of the intermediate bearing 17 faces the outer surface 19 a of the stopper 19. The stopper 19 is located between the rotation-side thrust surface 11 b of the rotation-side bearing 11, the fixed-side thrust surface 12 b of the fixed-side bearing 12, and the inner surface 17 c of the intermediate bearing 17. However, the positional relationship between the intermediate bearing 17 and the stopper 19 is not limited to this embodiment. In one embodiment, the stopper 19 may be disposed outside the intermediate bearing 17 in a direction perpendicular to the axis of the impeller 1. That is, the intermediate bearing 17 may be disposed on the center side of the fixed-side bearing 12, and the stopper 19 may be disposed outside the intermediate bearing 17.

  FIG. 3 is an enlarged view of the intermediate bearing 17 and the stopper 19. As shown in FIG. 3, the stopper end surface 19b of the stopper 19 faces the rotation-side thrust surface 11b. The first distance D1 from the first bearing end surface 17a of the intermediate bearing 17 to the second bearing end surface 17b is greater than the second distance D2 from the fixed thrust surface 12b of the fixed bearing 12 to the stopper end surface 19b of the stopper 19. Is also big. That is, the axial thickness of the intermediate bearing 17 is larger than the distance from the fixed thrust surface 12b to the stopper end surface 19b. The second bearing end surface 17 b of the intermediate bearing 17 is closer to the rotation-side bearing 11 than the stopper end surface 19 b of the stopper 19, and a part of the inner surface 17 c of the intermediate bearing 17 is exposed from the stopper 19.

  As shown in FIG. 2, a first axial gap G <b> 1 is formed between the rotary bearing 11 and the stopper 19, and a second axial gap is formed between the impeller 1 and the motor casing 3. G2 is formed, and the first axial gap G1 is smaller than the second axial gap G2. Hereinafter, the first axial gap G1 may be simply referred to as a first gap G1, and the second axial gap G2 may be simply referred to as a second gap G2.

  The impeller 1 and the motor casing 3 are opposed to each other through the second gap G <b> 2, and the impeller 1 rotates when a rotating magnetic field generated by the motor stator 6 acts on the permanent magnet 5. The second gap G2 between the impeller 1 and the motor casing 3 is preferably as small as possible so as not to contact each other.

  A part of the liquid discharged from the impeller 1 is guided to the bearing assembly 10 through a minute gap G2 between the impeller 1 and the motor casing 3. When the rotation-side bearing 11 rotates together with the impeller 1, liquid dynamic pressure is generated between the rotation-side bearing 11 and the intermediate bearing 17 and / or between the intermediate bearing 17 and the fixed-side bearing 12. 1 is supported in a non-contact manner by the bearing assembly 10. With such a configuration, the tilting of the impeller 1 is limited by the bearing assembly 10.

  FIG. 4 is a view of the intermediate bearing 17 as seen from the axial direction. As shown in FIG. 4, the first bearing end surface 17a of the intermediate bearing 17 is formed with a plurality of grooves 30 for generating dynamic pressure. The plurality of grooves 30 extend radially. By providing such a plurality of grooves 30, it is possible to uniformly generate dynamic pressure between the first bearing end surface 17 a of the intermediate bearing 17 and the fixed thrust surface 12 b of the fixed bearing 12. In the present embodiment, three grooves 30 are provided, but the number of grooves is not limited to this embodiment. Although not shown, the second bearing end surface 17b of the intermediate bearing 17 is also provided with a plurality of grooves. Therefore, the dynamic pressure can be evenly generated between the second bearing end surface 17 b of the intermediate bearing 17 and the rotation-side thrust surface 11 b of the rotation-side bearing 11. Instead of providing a plurality of grooves on the first bearing end surface 17a and the second bearing end surface 17b, a plurality of grooves are provided on the rotation side thrust surface 11b of the rotation side bearing 11 and the fixed side thrust surface 12b of the fixed side bearing 12. Also good.

  If foreign matter is contained in the liquid transferred by the rotation of the impeller 1, the foreign matter may enter the bearing assembly 10. According to this embodiment, the bearing assembly 10 includes the intermediate bearing 17 disposed between the rotation-side thrust surface 11 b of the rotation-side bearing 11 and the fixed-side thrust surface 12 b of the fixed-side bearing 12. Accordingly, the foreign matter that has entered the bearing assembly 10 may be clogged in the gap between the rotation-side bearing 11 and the intermediate bearing 17 and / or the gap between the fixed-side bearing 12 and the intermediate bearing 17. The gap between the side bearing 11 and the fixed side bearing 12 is not clogged.

The intermediate bearing 17 is made of a softer material than the rotation side bearing 11 and the fixed side bearing 12. In one embodiment, the rotation-side bearing 11 and the fixed-side bearing 12 are made of a material having high sliding resistance and high wear resistance, for example, ceramic such as silicon carbide (SiC) or silicon dioxide (SiO ₂ ). Yes. The intermediate bearing 17 is made of a resin such as PTFE (polytetrafluoroethylene), PPS (polyphenylene sulfide), or nylon.

  The foreign matter that has entered the bearing assembly 10 may be clogged in the gap between the rotation-side bearing 11 and the intermediate bearing 17 and / or the gap between the fixed-side bearing 12 and the intermediate bearing 17. According to the present embodiment, since the intermediate bearing 17 is made of a softer material than the rotation-side bearing 11 and the fixed-side bearing 12, the intermediate bearing 17 can bury foreign matter therein. Therefore, the rotation of the impeller 1 can be prevented from being obstructed by the foreign matter, and as a result, the operation of the motor pump can be continued.

  As shown in FIG. 1, the pump device further includes an inverter device 26 that supplies current to the motor stator 6. The motor stator 6 has a stator core 6A and a plurality of stator coils 6B. The plurality of stator coils 6B are arranged in an annular shape. The impeller 1 and the motor stator 6 are arranged concentrically with the bearing assembly 10 and the suction port 15a.

  The stator coil 6 </ b> B is connected to the inverter device 26 via the lead wire 25. The inverter device 26 supplies current to the stator coil 6 </ b> B of the motor stator 6 to generate a rotating magnetic field in the motor stator 6. This rotating magnetic field acts on the permanent magnet 5 embedded in the impeller 1 and rotationally drives the impeller 1. The torque of the impeller 1 depends on the magnitude of current supplied to the motor stator 6. As long as the load applied to the impeller 1 is constant, the current supplied to the motor stator 6 is substantially constant while the impeller 1 rotates at a predetermined speed.

  When the impeller 1 rotates, the liquid is introduced into the liquid inlet of the impeller 1 from the suction port 15a. The liquid is pressurized by the rotation of the impeller 1 and discharged from the discharge port 16a. While the impeller 1 is transferring liquid, the back surface of the impeller 1 is pressed to the suction side (that is, toward the suction port 15a) by the pressurized liquid. Since the bearing assembly 10 is disposed on the suction side of the impeller 1, the bearing assembly 10 supports the thrust load of the impeller 1 from the suction side.

  FIG. 5 is a view showing the rotation-side bearing 11 in contact with the stopper 19. When the impeller 1 rotates, the rotation-side bearing 11 is in sliding contact with the intermediate bearing 17, or the intermediate bearing 17 that rotates together with the rotation-side bearing 11 is in sliding contact with the fixed-side bearing 12. At this time, since the first gap G <b> 1 (see FIG. 2) is formed between the rotation side bearing 11 and the stopper 19, the rotation side bearing 11 does not contact the stopper 19.

  Thus, the intermediate bearing 17 is rotatably disposed between the rotation-side thrust surface 11b and the fixed-side thrust surface 12b, and the first bearing end surface 17a and the second bearing end surface 17b are respectively fixed. The sliding contact with the side thrust surface 12b and the rotation side thrust surface 11b is possible. Therefore, when the slidability between any one of the bearing end faces 17a and 17b and any one of the thrust faces 12b and 11b deteriorates, the bearing end faces 17a and 17b The other surface and the other of the thrust surfaces 12b and 11b slide.

  If the operation of the motor pump is continued, the intermediate bearing 17 made of a soft material will eventually wear out. As described above, the first gap G1 between the rotation-side bearing 11 and the stopper 19 is smaller than the second gap G2 between the impeller 1 and the motor casing 3. Therefore, when the wear of the intermediate bearing 17 proceeds, the rotation-side bearing 11 contacts the stopper 19 before the impeller 1 contacts the motor casing 3. With such a configuration, the impeller 1 can be prevented from contacting the motor casing 3, and the impeller 1 and / or the motor casing 3 can be prevented from being damaged due to the contact between the impeller 1 and the motor casing 3. can do.

  When the rotating rotary bearing 11 is in sliding contact with the stopper 19, the load applied to the impeller 1 is increased, and the current supplied from the inverter device 26 to the motor stator 6 is increased. When the current supplied to the motor stator 6 exceeds a predetermined threshold value, the inverter device 26 stops supplying current to the motor stator 6 and stops the rotation of the impeller 1. The inverter device 26 may issue an alarm without stopping the rotation of the impeller 1, or may stop the rotation of the impeller 1 and issue an alarm. With such a configuration, the user can appropriately determine the replacement time of the intermediate bearing 17. The inverter device 26 has a function of stopping the rotation of the impeller 1 and issuing an alarm. Such a function is called an overload protection function of the inverter device 26.

  During operation of the pump device, when the rotating rotary bearing 11 is in sliding contact with the intermediate bearing 17 or when the intermediate bearing 17 rotating with the rotating bearing 11 is in sliding contact with the fixed bearing 12, the current slightly increases. . Accordingly, the predetermined threshold value is arbitrarily determined, but the value of the current slightly increased by the sliding contact between the rotation-side bearing 11 and the intermediate bearing 17 (or the sliding contact between the intermediate bearing 17 and the fixed-side bearing 12). A higher value is desirable.

  According to the present embodiment, it is possible to detect an abnormality of the bearing assembly 10 at low cost by using the above-described overload protection function. That is, in the configuration of Patent Document 1, the bearing wear detector detects the wear of the bearing based on the difference between the induced voltages of the plurality of induction sensors. However, in such a configuration, a plurality of sensor parts and a detection circuit are required, and the number of parts necessary for detecting bearing wear increases. Therefore, it is difficult to reduce the size of the entire apparatus. Further, in such a configuration, wiring work and assembly work become complicated, and initial adjustment is also required. According to the present embodiment, since such a complicated configuration is unnecessary, the pump device can be reduced in size and the cost can be reduced.

  Furthermore, in general, it is necessary to attach the sensor component to the pump device with high accuracy. However, according to the present embodiment, the sensor component is unnecessary, so the dimensions of the pump device can be reduced without considering the arrangement of the sensor component. It can be easily changed.

  FIG. 6 is a view showing another embodiment of the bearing assembly 10. In the present embodiment, members that are the same as or correspond to those in the above-described embodiment are assigned the same reference numerals, and redundant descriptions are omitted.

As shown in FIG. 6, the stopper 19 may be composed of a member different from the fixed side bearing 12. Also in this embodiment, the stopper 19 is made of a material having high sliding resistance and high wear resistance. In the embodiment described above, the stopper 19 is made of the same material as that of the fixed-side bearing 12. However, in this embodiment, the stopper 19 has a higher sliding resistance than the fixed-side bearing 12 and has a high wear resistance. It can comprise from the member which has. In one embodiment, the stopper 19 is made of silicon carbide (SiC), alumina (Al ₂ O ₃ ), silicon dioxide (SiO ₂ ), or stainless steel (SUS).

  The stopper 19 is configured to be removable from the fixed side bearing 12. Therefore, even if it is necessary to replace the stopper 19 due to wear of the stopper 19 due to sliding contact between the rotation-side bearing 11 and the stopper 19, it is not necessary to replace the entire fixed-side bearing 12. In this case, only the stopper 19 needs to be replaced. As a result, the cost required for replacement of the bearing assembly 10 can be reduced.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Impeller 2 Pump casing 3 Motor casing 5 Permanent magnet 6 Motor stator 6A Stator core 6B Stator coil 10 Bearing assembly 11 Rotating side bearing 11a Rotating side radial surface 11b Rotating side thrust surface 12 Fixed side bearing 12a Fixed side radial Surface 12b Fixed thrust surface 15 Suction port 16 Discharge port 17 Intermediate bearing 17a First bearing end surface 17b Second bearing end surface 17c Inner surface 19 Stopper 19a Outer surface 19b Stopper end surface 25 Lead wire 26 Inverter device 30 Groove

Claims (11)

A fixed-side bearing having a cylindrical fixed-side radial surface, and a fixed-side thrust surface located radially outward of the fixed-side radial surface;
A rotation-side bearing having a cylindrical rotation-side radial surface surrounding the fixed-side radial surface, and a rotation-side thrust surface located radially outside the rotation-side radial surface;
A bearing assembly comprising: an intermediate bearing disposed between the rotation-side thrust surface and the fixed-side thrust surface. A stopper having a stopper end surface protruding outward from the fixed-side radial surface;
The bearing assembly according to claim 1, wherein the intermediate bearing is disposed around the stopper. The intermediate bearing has a first bearing end surface that contacts the fixed-side thrust surface, and a second bearing end surface that contacts the rotating-side thrust surface,
The bearing assembly according to claim 2, wherein a distance from the first bearing end surface to the second bearing end surface is larger than a distance from the fixed-side thrust surface to a stopper end surface of the stopper.   The bearing assembly according to claim 2, wherein the stopper is configured integrally with the fixed-side bearing.   The bearing assembly according to claim 2, wherein the stopper is made of a member different from the fixed-side bearing.   The bearing assembly according to any one of claims 1 to 5, wherein the intermediate bearing is made of a softer material than the fixed side bearing and the rotation side bearing. The fixed side bearing and the rotary side bearing are made of ceramic,
The bearing assembly according to claim 6, wherein the intermediate bearing is made of resin. The intermediate bearing is rotatably disposed between the rotation-side thrust surface and the fixed-side thrust surface,
The intermediate bearing has a first bearing end surface capable of sliding contact with the fixed-side thrust surface and a second bearing end surface capable of sliding contact with the rotating-side thrust surface. 2. The bearing assembly according to 1. An impeller with a permanent magnet embedded therein;
A pump casing that houses the impeller;
A motor stator having a plurality of stator coils;
A motor casing that houses the motor stator;
The bearing assembly according to any one of claims 1 to 8, which supports the impeller.
The rotation side bearing of the bearing assembly is fixed to the impeller,
The pump device according to claim 1, wherein a fixed side bearing of the bearing assembly is fixed to the motor casing. The bearing assembly is a bearing assembly according to any one of claims 2 to 5,
A first axial gap is formed between the rotation side bearing and the stopper,
A second axial gap is formed between the impeller and the motor casing,
The pump device according to claim 9, wherein the first axial gap is smaller than the second axial gap. An inverter device for supplying current to the motor stator;
The inverter device stops the supply of current to the motor stator when the rotation-side bearing contacts the stopper and the current supplied to the motor stator exceeds a predetermined threshold value. The pump device according to claim 10.

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