Bearing structure of canned motor pump

Abstract

A canned motor pump (100) comprises: bearings (3a, 3b) for rotatably supporting a rotating shaft (2) in a direction vertical to the axial direction via sleeves (4a, 4b); bearing-supported members (6a, 6b) provided around the rotating shaft (2) so as to rotate integrally with the rotating shaft (2) and rotatably supported by the bearings (3a, 3b) in the axial direction; and bearing-supported member housings (7a, 7b) which are provided on the rotating shaft (2) and in which the bearing-supported members (6a, 6b) are fitted from opening portions (43a, 43b). The bearing structure (1) of the canned motor pump (100) is formed such that: the inner diameters of the bearing-supported members (6a, 6b) are smaller than the outer diameters of the sleeves (4a, 4b); and the side surfaces of the sleeves (4a, 4b) more project on the bearing-supported member (6a, 6b) side than the side surfaces of the bearings (2) when the rotating shaft (2) farthest moves within the range of backlash in the opposite directions to the directions of the openings of the bearing-supported member housings (7a, 7b).

Description

[Technical field]

[0001] The present invention relates to a bearing structure for a canned motor pump. This application claims priority based on Patent Application No. 2021-150961, filed in Japan on September 16, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, there has been known a canned motor pump that includes a sliding bearing (hereinafter referred to as a "radial bearing") that supports the rotating shaft in a direction perpendicular to the axial direction, and a sliding bearing (hereinafter referred to as a "thrust bearing") that is fixed to the rotating shaft and supported in the axial direction by the radial bearing (see, for example, Patent Document 1).

[0003] In the canned motor pump disclosed in Patent Document 1, the radial bearing is fitted into a housing formed in the motor casing, and the thrust bearing is fitted into a housing formed in a member fixed to the rotating shaft. The abutment surface of the thrust bearing abuts against the side surface of the radial bearing in the axial direction, thereby restricting the axial movement of the rotating shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3768913 Summary of the Invention [Problem to be solved by the invention]

[0005] By the way, canned motor pumps are sometimes used to pump liquids whose temperature changes greatly. For example, when a canned motor pump is used in a temperature regulator such as a chiller, the canned motor pump may pump liquid whose temperature changes repeatedly within a range of -50°C to 150°C.

[0006] In a canned motor pump, due to its structure, part of the pumped liquid passes around the bearings, and when the liquid repeatedly undergoes large temperature changes, the housing of the thrust bearing and other parts repeatedly expand and contract due to temperature changes. When the housing of the thrust bearing expands and contracts, the thrust bearing may move toward the opening side of the housing.

[0007] The principle of movement of a thrust bearing press-fitted into a housing will be explained with reference to Figure 9. Here, the explanation will be made on the premise that, at room temperature, the outer periphery of the thrust bearing and the housing are in an interference fit state, and the inner periphery of the thrust bearing and the housing are in a clearance fit state.

[0008] First, when the housing 90 expands, the opening 91 of the housing 90 expands in diameter like a trumpet, as shown in FIG. 9(a). The degree of expansion tends to be greater as the temperature rise increases and as the thickness of the member on the outer periphery of the housing 90 becomes thinner. When the opening 91 expands in diameter like a trumpet, the thrust bearing 92 that was pressed in becomes easier to move because the pressure from the housing 90 weakens. Since a gap is generated between the inner diameter side surface of the thrust bearing 92 and the inner diameter side surface of the housing, when the thrust bearing 92 rotates together with the rotating shaft 95 and the housing 90 in this state, the thrust bearing 92 becomes eccentric as shown in FIG. 9(b) and the outer periphery of the thrust bearing 92 collides with the inclined housing 90. At this time, the thrust bearing 92 receives a force oblique to the axial direction from the inclined housing 90 as shown by the arrow, and gradually moves toward the opening 91.

[0009] When the temperature of the pumped liquid drops, as shown in FIG. 9(c), the housing 90 contracts and returns to its original shape, and the outer periphery of the thrust bearing and the housing return to their tight fit.

[0010] Thereafter, each time the housing expands in accordance with a change in temperature of the pumped liquid, the thrust bearing 92 approaches the radial bearing 94, and eventually, as shown in Fig. 9(d), the thrust bearing 92 moves to a position where it comes into contact with the radial bearing 94. As a result, the required gap between the radial bearing 94 and the thrust bearing 92 disappears. If the gap between the radial bearing 94 and the thrust bearing 92 disappears, the axial play of the rotating shaft 95 disappears, and there is a risk that the rotation of the rotating shaft 95 will be hindered.

[0011] The above-mentioned phenomenon in which the thrust bearing moves toward the opening side of the housing is not limited to the case where the thrust bearing is press-fitted into the housing. For example, the above-mentioned phenomenon can also occur when a ring that is elastically deformable in the radial direction, such as a tolerance ring, is interposed between the thrust bearing and the housing.

[0012] The present invention has been devised in view of the above problems, and aims to provide a bearing structure for a canned motor pump that can prevent the thrust bearing from moving excessively toward the opening side of the housing. Hereinafter, the radial bearing will be referred to simply as the "bearing" and the thrust bearing will be referred to as the "supported member". [Means for solving the problem]

[0013] The bearing structure of the canned motor pump according to the first aspect of the present invention is applied to a canned motor pump including a rotating shaft that rotates integrally with a rotor of a motor unit, a sleeve that is provided around the rotating shaft so as to rotate integrally with the rotating shaft, a bearing that rotatably supports the rotating shaft in a direction perpendicular to the axial direction via the sleeve, an annular bearing-supported member that is provided around the rotating shaft so as to rotate integrally with the rotating shaft and rotatably supported in the axial direction by the bearing, a bearing-supported member housing that is provided on the rotating shaft so as to rotate integrally with the rotating shaft and into which the bearing-supported member is fitted from an opening that opens to one side in the axial direction, and an impeller that rotates integrally with the rotating shaft. The inner diameter of the bearing-supported member is smaller than the outer diameter of the sleeve. The bearing structure of the canned motor pump is configured such that when the rotating shaft moves to the maximum extent within the range of play in the direction opposite to the opening direction of the bearing-supported member housing, the side surface of the sleeve protrudes toward the bearing-supported member more than the side surface of the bearing.

[0014] According to the bearing structure of the canned motor pump having such a configuration, the bearing supported member can be prevented from moving excessively toward the opening side of the housing.

[0015] A bearing structure for a canned motor pump according to a second aspect of the present invention is the bearing structure for a canned motor pump according to the first aspect, wherein the housing for the bearing-supported member has an extension portion extending axially between the bearing-supported member and the rotating shaft, and the axial length of the extension portion is longer than the axial length of the bearing-supported member.

[0016] A bearing structure for a canned motor pump according to a third aspect of the present invention is the bearing structure for a canned motor pump according to the first aspect, in which the bearing-supported member is fitted into the housing for the bearing-supported member via an elastic ring for the bearing-supported member that is capable of elastic deformation in the radial direction.

[0017] The bearing structure for a canned motor pump according to a fourth aspect of the present invention is the bearing structure for the canned motor pump according to the first aspect, in which an elastic structure for the bearing-supported member is provided within the housing for the bearing-supported member, which applies an elastic reaction force in the axial direction to the bearing-supported member when the bearing-supported member is pressed.

[0018] A bearing structure for a canned motor pump according to a fifth aspect of the present invention is the bearing structure for a canned motor pump according to the fourth aspect, in which the elastic structure for the bearing-supported member applies the elastic reaction force in the axial direction to the bearing-supported member, and is an elastic body provided between the housing for the bearing-supported member and the rotor side of the motor section of the bearing-supported member. Effect of the Invention

[0019] According to the bearing structure for the canned motor pump of the present invention, the bearing supported member can be prevented from moving excessively toward the opening side of the housing. [Brief description of the drawings]

[0020] [Figure 1] 1 is an overall cross-sectional view of a canned motor pump according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of part A in FIG. [Diagram 3] FIG. 2 is an enlarged view of part B in FIG. [Figure 4] 2 is an enlarged view of part A in FIG. 1, showing a case where a bearing-supported member has moved; FIG. [Diagram 5] 2 is an enlarged view of a portion B in FIG. 1, showing a case where a bearing-supported member has moved. FIG. [Figure 6] FIG. 11 is an overall cross-sectional view of a canned motor pump according to another embodiment. [Figure 7] 7 is an enlarged view of part A in FIG. 6, showing a case where a bearing-supported member has moved. FIG. [Figure 8] 7 is an enlarged view of part B in FIG. 6, showing a case where the bearing-supported member has moved. FIG. [Figure 9]FIG. 1 is a diagram for explaining a problem in a conventional example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, a bearing structure for a canned motor pump according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the bearing structure 1 for a canned motor pump is composed of a rotating shaft 2, bearings 3a, 3b, sleeves 4a, 4b, bearing-supported members 6a, 6b, and housings 7a, 7b for the bearing-supported members, which are included in a canned motor pump 100.

[0022] The bearing structure shown in the area indicated by the symbol A in Figure 1 is referred to as the first bearing structure, and the associated components are each referred to as components on the first bearing structure side, and the bearing structure shown in the area indicated by the symbol B in Figure 1 is referred to as the second bearing structure, and the associated components are each referred to as components on the second bearing structure side.

[0023] The canned motor pump 100 includes a motor section 8 and a pump section 9 driven by the motor section 8. The motor section 8 includes a rotor 12 and a stator 13 provided on the outer periphery of the rotor 12. The rotor 12 has a magnet 26 and is fixed to a rotating shaft 2. The rotating shaft 2 is supported by bearings 3a and 3b attached to bearing housings 14a and 14b via sleeves 4a and 4b.

[0024] The pump section 9 has an impeller 16 and a pump casing 18. The impeller 16 is fixed to the rotary shaft 2 and rotates integrally with the rotary shaft 2. An impeller accommodating space 17 for accommodating the impeller 16 is formed within the pump casing 18.

[0025] The motor unit 8 has a rotor 12 that rotates integrally with the rotating shaft 2, and a stator 13. The rotor 12 is accommodated inside a cylindrical stator can 19. The stator 13 is disposed outside the stator can 19 and inside a cylindrical frame 21, at a position corresponding to the rotor 12 inside the stator can 19. The stator can 19 and stator side plates 27a, 27b provided at both ends of the stator can 19 are hermetically connected by welding. The stator side plates 27a, 27b and the frame 21 are sealed with O-rings 28 arranged at the ends of the stator side plates 27a, 27b, and are hermetically connected by partial welding. The stator side plates 27a, 27b and the motor brackets 20a, 20b seal an internal space 31 formed inside the stator can 19 with O-rings 29 arranged outside the stator side plates 27a, 27b. Specifically, motor brackets 20a, 20b are fastened with a plurality of bolts to sandwich the entire motor unit 8 between motor brackets 20a, 20b, thereby sealing the internal space 31. Hereinafter, motor bracket 20a will also be referred to as the "first motor bracket 20a," and motor bracket 20b will also be referred to as the "second motor bracket 20b."

[0026] The rotor 12 includes a rotor can 22, a rotor side plate 23, a rotor body 24, a yoke 11, a magnet 26, etc., and is fixed to the rotating shaft 2. The rotor can 22 is joined to the rotor body 24 and the rotor side plate 23 by welding. The rotor side plate 23 is joined to the rotor body 24 by welding. As a result, the yoke 11 and the magnet 26 are surrounded and sealed by the rotor can 22, the rotor side plate 23, and the rotor body 24. The gap between the pump casing 18 and the second motor bracket 20b is sealed by an O-ring 32 disposed at the end of the second motor bracket 20b, and the impeller accommodating space 17 is sealed.

[0027] The stator 13 is composed of an electromagnetic coil and the like. When a driving current is supplied to the stator 13, the rotor 12 and the rotating shaft 2 are driven to rotate.

[0028] An inlet 37 is provided on the side of the pump casing 18 in which the impeller 16 is housed, through which liquid flows into the canned motor pump 100 from outside the canned motor pump 100. In addition, an outlet 39 is provided on the top surface of the pump casing 18, through which the liquid that has flowed into the canned motor pump 100 is discharged. Note that some of the liquid that has flowed into the canned motor pump 100 flows through the internal space 31, and passes between the bearings 3a, 3b, the sleeves 4a, 4b, the bearing-supported members 6a, 6b, and the housings for the bearing-supported members 7a, 7b.

[0029] As shown in Figs. 1, 2 and 3, the bearings 3a and 3b support the rotating shaft 2 via the sleeves 4a and 4b in a direction perpendicular to the axial direction so as to be freely rotatable. The bearings 3a and 3b are provided on both sides of the rotor 12 in the axial direction. The bearings 3a and 3b are cylindrical, and radially extending grooves 41a and 41b are formed on the axial end faces. In addition, helical grooves 42a and 42b are formed on the inner peripheral surfaces of the bearings 3a and 3b. Fluid flows through both the radially extending grooves 41a and 41b and the helical grooves 42a and 42b. The grooves 41a and 41b promote lubrication of the sliding surfaces between the bearing-supported members 6a and 6b and the bearings 3a and 3b. The helical grooves 42a and 42b promote lubrication of the sliding surfaces between the bearings 3a and 3b and the sleeves 4a and 4b.

[0030] The bearings 3a, 3b are fitted in bearing housings 14a, 14b provided on the motor brackets 20a, 20b via elastic bearing rings 46a, 46b.

[0031] The elastic bearing rings 46a, 46b are cylindrical rings that can be elastically deformed in the radial direction. Since the bearings 3a, 3b are fitted into the bearing housings 14a, 14b via the elastic bearing rings 46a, 46b, the bearings 3a, 3b are prevented from rattling relative to the bearing housings 14a, 14b, and the difference in thermal expansion coefficient between the bearing housings 14a, 14b and the bearings 3a, 3b is absorbed. In this embodiment, tolerance rings are used as the elastic bearing rings 46a, 46b.

[0032] A rotor 12, housings 7a, 7b for the bearing-supported member, and sleeves 4a, 4b are arranged in the axial direction on the rotating shaft 2. The housings 7a, 7b for the bearing-supported member are arranged on each end of the rotor 12. The rotor 12 and the housings 7a, 7b for the bearing-supported member are arranged between the two sleeves 4a, 4b.

[0033] As shown in FIG. 1, the one sleeve 4a and the rotor body 24 on which the one housing for the supported member 7a is formed are sandwiched between a step formed on the rotating shaft 2 and a washer. That is, the one sleeve 4a and the rotor body 24 are fixed so as not to move around the axis and in the axial direction relative to the rotating shaft 2 by tightening a nut N screwed onto one end of the rotating shaft 2. The other sleeve 4b and the member on which the other housing for the supported member 7b is formed are sandwiched, together with other members, between a step formed on the rotating shaft 2 and a washer. That is, the other sleeve 4b and the member on which the other housing for the supported member 7b is formed are fixed so as not to move around the axis and in the axial direction relative to the rotating shaft 2 by tightening a nut N screwed onto the other end of the rotating shaft 2.

[0034] The sleeves 4a and 4b are cylindrical members provided around the rotating shaft 2 so as to rotate integrally with the rotating shaft 2, and arranged so that their outer peripheral surfaces are in sliding contact with the inner peripheral surfaces of the bearings 3a and 3b. Hereinafter, the sleeve 4a will also be referred to as the "first sleeve 4a," and the sleeve 4b will also be referred to as the "second sleeve 4b."

[0035] 2 and 3, the housings 7a, 7b for the bearing-supported members are provided on the rotating shaft 2 so as to rotate integrally with the rotating shaft 2, and the bearing-supported members 6a, 6b are fitted into openings 43a, 43b that open to one side in the axial direction. A gap is formed between the bearing-supported members 6a, 6b and surfaces 49a, 49b of the housings 7a, 7b for the bearing-supported members on the rotating shaft 2 side.

[0036] The housings 7a, 7b for the bearing-supported member form annular grooves including cylindrical surfaces 48a, 48b away from the rotating shaft 2, cylindrical surfaces 49a, 49b closer to the rotating shaft 2, and surfaces 50a, 50b perpendicular to the axial direction. One opening 43a is formed on the side of one bearing 3a, and the other opening 43b is formed on the side of the other bearing 3b.

[0037] The bearing-supported members 6a, 6b are held in the axial direction of the rotating shaft 2 via the bearing-supported member housings 7a, 7b. As a result, the rotating shaft 2 is supported in the axial direction on the side surfaces of the bearings 3a, 3b via the bearing-supported members 6a, 6b. Hereinafter, the bearing-supported member housing 7a will also be referred to as the "first bearing-supported member housing 7a," and the bearing-supported member housing 7b will also be referred to as the "second bearing-supported member housing 7b."

[0038] The bearing-supported members 6a, 6b are provided around the rotating shaft 2 so as to rotate integrally with the rotating shaft 2, and are rotatably supported in the axial direction by bearings 3a, 3b. Annular members are used as the bearing-supported members 6a, 6b. The bearing-supported members 6a, 6b are fitted into bearing-supported member housings 7a, 7b provided on the rotating shaft 2 via bearing-supported member elastic rings 47a, 47b. Hereinafter, the bearing-supported member 6a will also be referred to as the "first bearing-supported member 6a," and the bearing-supported member 6b will also be referred to as the "second bearing-supported member 6b."

[0039] The elastic rings 47a, 47b for the bearing-supported members are cylindrical rings that can be elastically deformed in the radial direction. The bearing-supported members 6a, 6b are fitted into the housings 7a, 7b for the bearing-supported members via the elastic rings 47a, 47b for the bearing-supported members, so that the rattle of the bearing-supported members 6a, 6b relative to the housings 7a, 7b for the bearing-supported members is prevented, and the difference in thermal expansion coefficient between the housings 7a, 7b for the bearing-supported members and the bearing-supported members 6a, 6b is absorbed. In this embodiment, tolerance rings are used as the elastic rings 47a, 47b for the bearing-supported members.

[0040] The effect of the present embodiment can be obtained even if the bearing-supported members 6a, 6b are press-fitted into the housings 7a, 7b for the bearing-supported members as in the conventional example. The effect of the present embodiment can be obtained even if the bearing-supported members 6a, 6b are fitted into the housings 7a, 7b for the bearing-supported members via set screws instead of the elastic rings 47a, 47b for the bearing-supported members. As an example of fitting into the housings 7a, 7b for the bearing-supported members via set screws, a female screw hole penetrating the centrifugal side member of the housings 7a, 7b for the bearing-supported members can be formed, and a set screw is screwed into the female screw hole and tightened to hold the bearing-supported members 6a, 6b in the housings 7a, 7b for the bearing-supported members.

[0041] The inner diameter of the supported members 6a, 6b is smaller than the outer diameter of the sleeves 4a, 4b. Therefore, locking steps 51a, 51b consisting of the end faces of the sleeves 4a, 4b are formed between the inner diameter side surface 49a of the housings 7a, 7b for the supported members and the outer circumferential surfaces of the sleeves 4a, 4b. Hereinafter, the locking step 51a is also referred to as the "first locking step 51a," and the locking step 51b is also referred to as the "second locking step 51b."

[0042] As shown in Figures 4 and 5, even if the bearing-supported members 6a, 6b move toward the opening direction of the housings 7a, 7b for the bearing-supported members, the inner diameter side ends of the bearing-supported members 6a, 6b are engaged with the locking steps 51a, 51b of the sleeves 4a, 4b, thereby preventing the bearing-supported members 6a, 6b from jumping out of the housings 7a, 7b for the bearing-supported members.

[0043] In the canned motor pump bearing structure 1, when the rotating shaft 2 moves the maximum within the range of play in the direction opposite to the opening direction of the housing 7a for one of the supported members (i.e., to the right in Fig. 1), the side surface of one sleeve 4a protrudes toward the side of one of the supported members 6a more than the side surface of one of the bearings 3a. Also, in the canned motor pump bearing structure 1, when the rotating shaft 2 moves the maximum within the range of play in the direction opposite to the opening direction of the housing 7b for the other supported member (i.e., to the left in Fig. 1), the side surface of the other sleeve 4b protrudes toward the side of the other supported member 6b more than the side surface of the other bearing 3b.

[0044] In the canned motor pump 100 of this embodiment, the rotating shaft 2 moves toward the inlet 37 due to the axial pressure difference received from the fluid during operation. When the rotating shaft 2 moves as far as possible toward the inlet 37 within the range of play, the second bearing-supported member 6b comes into contact with the second bearing 3b. In this state, the first bearing-supported member 6a on the opposite side is designed to be a predetermined distance away from the first bearing 3a. However, as explained based on FIG. 9, even in this state, if the first bearing-supported member 6a jumps out of the housing 7a and comes into contact with the first bearing 3a, the axial play of the rotating shaft 2 disappears and the rotation of the rotating shaft 2 is hindered.

[0045] Therefore, in order to prevent the first bearing-supported member 6a from jumping out of the housing 7a for the first bearing-supported member during operation, the side surface of the first sleeve 4a is configured to protrude further toward the first bearing-supported member 6a than the side surface of the first bearing 3a when the rotating shaft 2 moves the maximum within the range of play in the direction opposite to the opening direction of the housing 7a for the first bearing-supported member, as shown in Fig. 4. In other words, the dimensions of each member are designed to achieve this.

[0046] If the side of the first sleeve 4a is configured to protrude toward the first bearing-supported member 6a further than the side of the first bearing 3a when the rotating shaft 2 moves furthest toward the inlet 37, the first bearing-supported member 6a will be engaged with the first locking step 51a before coming into contact with the first bearing 3a, preventing the first bearing-supported member 6a from jumping out of the housing 7a for the first bearing-supported member.

[0047] In the above description, the first side configuration consisting of the first bearing 3a, the first sleeve 4a, the first bearing-supported member 6a, and the housing 7a for the first bearing-supported member has been described, but the same is true for the second side configuration consisting of the second bearing 3b, the second sleeve 4b, the second bearing-supported member 6b, and the housing 7b for the second bearing-supported member. That is, since the first side configuration and the second side configuration are arranged symmetrically when viewed from a direction perpendicular to the axial direction as shown in Fig. 1, even when the rotating shaft 2 moves to the farthest side opposite the inlet 37 within the range of play as shown in Fig. 5, if the side surface of the second sleeve 4b is configured to protrude toward the second bearing-supported member 6b more than the side surface of the second bearing 3b, the second bearing-supported member 6b is locked to the second locking step 51b before coming into contact with the second bearing 3b, and the second bearing-supported member 6b is prevented from jumping out of the housing 7b for the second bearing-supported member.

[0048] During operation of the canned motor pump 100, the rotating shaft 2 moves toward the inlet 37, but during stoppage of the canned motor pump 100, thrust due to differential pressure does not act on the rotating shaft 2, so the rotating shaft 2 can move in either axial direction. In this case, if the second bearing-supported member 6b protrudes from the housing 7b for the second bearing-supported member and abuts against the second bearing 3b, the rotation of the rotating shaft 2 may be hindered because the axial play of the rotating shaft 2 disappears. However, as described above, even in this case, if the side surface of the second sleeve 4b is configured to protrude toward the second bearing-supported member 6b more than the side surface of the second bearing 3b, the second bearing-supported member 6b is locked to the second locking step 51b before abutting against the second bearing 3b. In other words, the second bearing-supported member 6b can be prevented from protruding from the housing 7b for the second bearing-supported member and abutting against the second bearing 3b.

[0049] A modification of this embodiment will now be described.

[0050] The bearing structure according to the modified example is the same as that of the embodiment described above, but with the addition of elastic structures 52a, 52b for the bearing-supported member and elastic structures 53a, 53b for the bearings.

[0051] The elastic structures 52a, 52b for the bearing-supported members apply an elastic reaction force in the axial direction to the bearing-supported members 6a, 6b when the bearing-supported members 6a, 6b are pressed axially by the bearings 3a, 3b, as shown in Figure 6, and are elastic bodies provided between the housings 7a, 7b for the bearing-supported members and the rotor 12 side of the motor section 8 of the bearing-supported members 6a, 6b.

[0052] The bearing elastic structures 53a, 53b apply an elastic reaction force in the axial direction to the bearings 3a, 3b when the bearings 3a, 3b are pressed in the axial direction by the bearing supported members 6a, 6b.

[0053] The elastic bearing structures 53a, 53b apply an elastic reaction force in the axial direction to the bearings 3a, 3b, and are elastic bodies provided between the bearing housings 14a, 14b and the motor brackets 20a, 20b sides of the bearings 3a, 3b.

[0054] Although the elastic structures 52a, 52b for the bearing-supported member and the elastic structures 53a, 53b for the bearings are both drawn diagrammatically in the drawings, they are not limited to a specific form as long as the bearings 3a, 3b are members that generate an elastic reaction force in the axial direction against the bearing-supported members 6a, 6b. For example, an annular member that forms a waveform in the circumferential direction (e.g., a member shaped like a wave washer), a coil spring, or the like can be used as the elastic structures 52a, 52b for the bearing-supported member and the elastic structures 53a, 53b for the bearings.

[0055] In the bearing structure 1 of the canned motor pump 100, due to the influence of dimensional tolerances of various parts, the side surfaces of the bearings 3a, 3b and the abutment surfaces of the supported members 6a, 6b may not make surface contact when they are inclined relative to one another. In this case, wear progresses on parts of the side surfaces of the bearings 3a, 3b and parts of the abutment surfaces of the supported members 6a, 6b, gradually increasing the initial axial play of the rotating shaft 2 and the inclination of the rotating shaft 2 relative to the initial axial direction, which may result in a deterioration in the performance of the canned motor pump 100.

[0056] In order to solve this problem, the elastic structures 52a, 52b for the bearing-supported member and the elastic structures 53a, 53b for the bearing are arranged at both ends of the first bearing-supported member 6a and the first bearing 3a, and at both ends of the second bearing-supported member 6b and the second bearing 3b. By providing the elastic structures 52a, 52b for the bearing-supported member and the elastic structures 53a, 53b for the bearing, the bearings 3a, 3b and the bearing-supported members 6a, 6b can abut against each other while tilting at a small angle in the axial direction so that the opposing surfaces are in surface contact, and can be in appropriate surface contact. In this way, the elastic structures 52a, 52b for the bearing-supported member and the elastic structures 53a, 53b for the bearing have the function of preventing wear caused by the bearings 3a, 3b coming into one-sided contact with the bearing-supported members 6a, 6b.

[0057] The elastic structures arranged at the ends of the bearing-supported members 6a, 6b are referred to as elastic structures 52a, 52b for the bearing-supported members, and the elastic structures arranged at the ends of the bearings 3a, 3b are referred to as elastic structures 53a, 53b for the bearings.

[0058] In the modified embodiment, if there is no locking step 51a shown in Fig. 7, when a gap occurs between the first bearing 3a and the first supported member 6a, the first supported member 6a may be pushed out of the housing 7a for the first supported member by the elastic force of the elastic structure 52a for the first supported member. Also, if there is no locking step 51b shown in Fig. 8, when a gap occurs between the second bearing 3b and the second supported member 6b, the second supported member 6b may be pushed out of the housing 7b for the second supported member by the elastic force of the elastic structure 52b for the second supported member.

[0059] However, due to the presence of the locking steps 51a, 51b, even if the bearing-supported members 6a, 6b are pressed against the elastic structures 52a, 52b for the bearing-supported members, the bearing-supported members 6a, 6b are locked by the locking steps 51a, 51b and are prevented from jumping out of the housings 7a, 7b for the bearing-supported members.

[0060] The housings 7a, 7b for the bearing-supported members have extending portions 54a, 54b extending in the axial direction between the bearing-supported members 6a, 6b and the rotating shaft 2. Hereinafter, the extending portion 54a will also be referred to as the "first extending portion 54a," and the extending portion 54b will also be referred to as the "second extending portion 54b."

[0061] The axial length of the first extending portion 54a is longer than the axial length of the first bearing-supported member 6a, and the axial length of the second extending portion 54b is longer than the axial length of the second bearing-supported member 6b.

[0062] If the locking steps 51a, 51b are formed, the outer end faces of the sleeves 4a, 4b and the inner end faces of the bearing-supported members 6a, 6b may come into contact with each other, causing the bearing-supported members 6a, 6b to be fixed in the housings 7a, 7b for the bearing-supported members. If the bearing-supported members 6a, 6b are fixed in the housings 7a, 7b for the bearing-supported members, the elastic structures 52a, 52b for the bearing-supported members, which press the bearing-supported members 6a, 6b to tilt them by a small angle and bring them into surface contact with the bearings 3a, 3b, cannot function.

[0063] However, by providing the first extension portion 54a, a gap is formed between the first sleeve 4a and the first supported member 6a. Similarly, by providing the second extension portion 54b, a gap is formed between the second sleeve 4b and the second supported member 6b. This prevents the supported members 6a, 6b from being fixed within the supported member housings 7a, 7b. This allows the supported member elastic structures 52a, 52b to function.

[0064] The present invention described above can be implemented in various other forms without departing from the spirit, intent, or main features of the present invention. Therefore, the above-described embodiments are merely examples in all respects and should not be interpreted as being limited. In other words, the above-described embodiments are merely examples. [Industrial Applicability]

[0065] The present invention can be applied to, for example, the bearing structure of a canned motor pump. [Explanation of symbols]

[0066] 100 Canned motor pump 1. Bearing structure of canned motor pump 2 Rotation Axis 3a,3b Bearing 4a,4b Sleeve 6a, 6b Bearing supported member 7a, 7b Housing for bearing supported member 8 Motor section 9. Pump section 12 Rotor 14a, 14b Bearing housing 16 Impeller 43a,43b opening 46a, 46b Elastic ring for bearing 47a, 47b Elastic ring for bearing supported member 52a, 52b Elastic structure for bearing supported member 54a,54b Extension part

Claims

1. A rotating shaft that rotates together with the rotor of the motor unit; a sleeve provided around the rotating shaft so as to rotate integrally with the rotating shaft; a bearing that rotatably supports the rotating shaft via the sleeve in a direction perpendicular to the axial direction; a ring-shaped bearing-supported member that is provided around the rotating shaft so as to rotate integrally with the rotating shaft and is rotatably supported in the axial direction by the bearing; a housing for a bearing-supported member provided on the rotating shaft so as to rotate integrally with the rotating shaft, the housing having an opening on one side in the axial direction into which the bearing-supported member is fitted; an impeller that rotates integrally with the rotary shaft; In a canned motor pump comprising: The inner diameter of the bearing supported member is smaller than the outer diameter of the sleeve, When the rotating shaft moves to the maximum extent within a range of play in a direction opposite to an opening direction of the housing for the supported member, a side surface of the sleeve protrudes toward the supported member more than a side surface of the bearing. A bearing structure for a canned motor pump.

2. 2. The bearing structure for a canned motor pump according to claim 1, the housing for the bearing-supported member has an extension portion extending in the axial direction between the bearing-supported member and the rotating shaft, The axial length of the extension portion is longer than the axial length of the bearing supported member. A bearing structure for a canned motor pump.

3. 2. The bearing structure for a canned motor pump according to claim 1, the support member is fitted into the housing via an elastic ring for the support member that is elastically deformable in a radial direction; A bearing structure for a canned motor pump.

4. 2. The bearing structure for a canned motor pump according to claim 1, The housing for the bearing-supported member is provided with an elastic structure for the bearing-supported member, which applies an elastic reaction force in the axial direction to the bearing-supported member when the bearing presses the bearing-supported member. A bearing structure for a canned motor pump.

5. 5. The bearing structure for a canned motor pump according to claim 4, The elastic structure for the bearing-supported member applies the elastic reaction force in the axial direction to the bearing-supported member, and is an elastic body provided between the housing for the bearing-supported member and the rotor side of the motor unit of the bearing-supported member. A bearing structure for a canned motor pump.

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