JP2016188619A - pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump capable of rotatably supporting a rotor by suppressing the contact of the rotor and a stator even under a condition in which a dynamic pressure bearing is not established.SOLUTION: A pump is equipped with a first member having an outer surface disposed around a rotary shaft, and a second member disposed around the first member. The first member and the second member can be relatively rotated. The second member has a first inner surface which forms a bearing clearance between the outer surface and the first inner surface, a second inner surface which forms an inlet side channel of second dimensions larger than first dimensions of the bearing clearance between the outer surface and the second inner surface on an inlet side of the bearing clearance into which a lubrication liquid floes, and a third inner surface which forms an outlet side channel of third dimensions larger than the first dimensions between the outer surface and the third inner surface on the outlet side of the bearing clearance from which the lubrication liquid flows out. In the bearing clearance, in order to make the lubrication liquid flow in an axial direction parallel with the rotary shaft, the pressure of the inlet side channel is made higher than that of the outlet side channel.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pump.

  A pump that rotatably supports a rotor using a dynamic pressure bearing is known (see Patent Document 1). The hydrodynamic bearing forms a film of lubricating liquid in the bearing gap between the rotor and the stator.

JP 2013-064327 A

  The hydrodynamic bearing is established by satisfying various conditions such as the number of rotations of the rotor per unit time, the size of the bearing gap, the viscosity of the lubricating liquid, and the bearing area. That is, the hydrodynamic bearing is established under the constraints of these conditions. For this reason, for example, when the rotational speed of the rotor is low at the time of starting up the pump, the rotor and the stator come into contact under conditions where the hydrodynamic bearing is not established.

  An object of this invention is to provide the pump which can support a rotor rotatably, suppressing the contact with a rotor and a stator on the conditions where a dynamic-pressure bearing is not materialized.

  The present invention includes a first member having an outer surface disposed around a rotation shaft, and a second member disposed around the first member, wherein the first member and the second member are relatively The second member is rotatable, and the second member includes a first inner surface that forms a bearing gap with the outer surface, and an outer surface on the inlet side of the bearing gap into which lubricating liquid flows. A third dimension larger than the first dimension between a second inner surface forming an inlet-side flow path having a second dimension larger than one dimension and the outer surface on the outlet side of the bearing gap from which the lubricating liquid flows out. A third inner surface that forms an outlet-side flow path of the outlet-side flow path, and the pressure of the inlet-side flow path is adjusted so that the lubricating liquid flows in an axial direction parallel to the rotation axis in the bearing gap. A pump is provided that is higher than the pressure in the passage.

  According to the present invention, when one of the first member and the second member is a rotor and the other is a stator, a pressure difference is provided between the inlet-side channel and the outlet-side channel of the bearing gap, By flowing the lubricating liquid in the axial direction, when the first member and the second member are relatively moved in the radial direction perpendicular to the rotation axis, a restoring force is generated to return the bearing gap to the original first dimension. . When the restoring force is generated, contact between the first member and the second member is suppressed. This restoring force is generated even when the relative rotational speed between the first member and the second member is low. Further, this restoring force is generated even if the first dimension of the bearing gap is large. Further, this restoring force is generated independently of the viscosity of the lubricating liquid. In this way, by setting the pressure on the inlet side flow path higher than the pressure on the outlet side flow path so that the lubricating liquid flows in the axial direction in the bearing gap, the conditions (dynamic speed, bearing gap Also in the dimension and the viscosity), the contact between the first member and the second member that rotate relative to each other is suppressed.

  In addition, since the first dimension of the bearing gap may be larger than the condition for establishing the hydrodynamic bearing, high smoothness or high machining accuracy is not required for the outer surface of the first member and the inner surface of the second member. Thereby, restrictions on processing of the first member and the second member are eased.

In the present invention, when the outer surface and the first inner surface are circular in a plane orthogonal to the rotation axis, when the first dimension is Cd and the diameter of the first member is d,
0.002 ≦ Cd / d ≦ 0.02
It is preferable to satisfy the following conditions.

  By making the first member columnar or cylindrical, and the second member and the cylindrical shape, a constant restoring force can be obtained regardless of the radial direction of the first member and the second member. Can do. Further, there is Cd / d as an element for obtaining a restoring force. Cd / d means the ratio of the first dimension of the bearing gap to the diameter of the first member. When Cd / d is smaller than 0.002, the bearing gap is too narrow, and the lubricating liquid may not smoothly flow in the axial direction in the bearing gap. As a result, there is a possibility that sufficient restoring force cannot be obtained. On the other hand, when Cd / d is larger than 0.02, the bearing gap is too wide, and a sufficient pressure difference between the inlet-side channel and the outlet-side channel cannot be obtained. It may not be obtained sufficiently. By satisfying the above-described conditions, a restoring force is obtained even under conditions where the hydrodynamic bearing is not established, and contact between the first member and the second member that rotate relative to each other is suppressed.

  In the present invention, it is preferable to use a working liquid to be conveyed as the lubricating liquid. By using the working liquid of the pump as the lubricating liquid, it is not necessary to provide the working liquid supply system and the lubricating liquid supply system separately, and the pressure difference of the lubricating liquid between the inlet side flow path and the outlet side flow path can be reduced. An external high-pressure pump or piping for obtaining is also unnecessary, and the pump can be made a simple structure.

  ADVANTAGE OF THE INVENTION According to this invention, the pump which can support a rotor rotatably by suppressing the contact with a rotor and a stator on the conditions where a dynamic pressure bearing is not materialized is provided.

FIG. 1 is a cross-sectional view showing a pump according to the first embodiment. FIG. 2 is a schematic diagram illustrating the pump according to the first embodiment. FIG. 3 is a schematic diagram illustrating the pump according to the first embodiment. FIG. 4 is a diagram illustrating the operation of the pump according to the first embodiment. FIG. 5 is a schematic diagram showing a pump according to the second embodiment.

  Embodiments according to the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. The components of the embodiments described below can be combined as appropriate. Some components may not be used.

<First Embodiment>
FIG. 1 is a cross-sectional view showing the pump 100. The pump 100 is a magnetic coupling pump that conveys a working liquid. The pump 100 includes a sealed impeller 10 and a pump casing 60 that rotatably supports the impeller 10 about a rotation axis AX. The impeller 10 is a rotor, and the pump casing 60 is a stator. Liquid bearings 1 </ b> A and 1 </ b> B are formed between the impeller 10 and the pump casing 60. The liquid bearing 1A and the liquid bearing 1B are formed at different positions in the axial direction parallel to the rotation axis AX. The liquid bearings 1 </ b> A and 1 </ b> B form a lubricating liquid film in the bearing gap 2 between the impeller 10 and the pump casing 60. The working liquid of the pump 100 is used as the lubricating liquid for the liquid bearings 1A and 1B.

  The pump casing 60 has a suction port 6 for sucking the working liquid and a discharge port 7 for discharging the working liquid. The suction port 6 is provided in the suction hose connection pipe part 62 to which the suction hose is connected. The discharge port 7 is provided in the discharge hose connection pipe part 9 to which the discharge hose is connected.

  In the following description, the suction port 6 side in the axial direction parallel to the rotation axis AX is the front side, and the opposite side is the rear side. The radial rotation axis AX side orthogonal to the rotation axis AX is defined as the inside, and the opposite side is defined as the outside.

  The impeller 10 has an impeller inlet 12 that faces the suction port 6 and the working liquid flows in, an impeller outlet 13 that faces the discharge port 7 and the working liquid flows out, and the impeller inlet 12 and the impeller outlet 13. And an impeller internal flow path Pr to be connected.

  The impeller 10 includes a plurality of blades 11, a front shroud 20 that covers the front side of the blades 11, and a rear shroud 40 that covers the rear side of the blades 11. The front and rear of the blades 11 are covered with the front shroud 20 and the rear shroud 40, whereby the hermetic impeller 10 is formed.

  The front shroud 20 includes an inlet tube portion 21 and a front plate portion 31 that covers the front side of the blade 11. The rear shroud 40 includes a rear plate portion 41 that covers the rear side of the blade 11 and a shaft portion 51 on which a plurality of driven magnets 19 are provided. The impeller inlet 12 is provided in the inlet tube portion 21. The impeller outlet 13 is provided between the front side plate portion 31 and the rear side plate portion 41. The plurality of blades 11 are disposed between the front plate portion 31 and the rear plate portion 41.

  The impeller internal flow path Pr includes a space inside the inlet cylinder portion 21 and a space between the front plate portion 31 and the rear plate portion 41.

  A through-hole 56 connected to the impeller internal flow path Pr is formed in the shaft portion 51. The rear end portion of the through hole 56 is connected to a space between the rear end surface 53 of the shaft portion 51 and the pump casing 60.

  An inlet tapered surface 24 is formed at the front end portion of the inlet cylinder portion 21. An arcuate surface 23 is formed at the boundary between the outer peripheral surface 22 of the inlet cylinder 21 and the tapered inlet surface 24. A front plate taper surface 33 is formed outside the front surface 32 of the front plate portion 31. A rear plate taper surface 43 is formed outside the rear surface 42 of the rear plate portion 41. A shaft taper surface 55 is formed inside the rear end surface 53 of the shaft portion 51. A circular arc surface 54 is formed at the boundary between the outer peripheral surface 52 of the shaft portion 51 and the shaft taper surface 55.

  The pump casing 60 includes a pump front casing 61 that covers the front shroud 20 and a pump rear casing 81 that covers the rear shroud 40.

  The pump front casing 61 is connected to the suction hose connection pipe part 62, the diameter expansion pipe part 65 connected to the rear end part of the suction hose connection pipe part 62, and the rear end part of the diameter expansion pipe part 65. The front bearing forming portion 67 disposed around the portion 21 and the front casing body portion 71 connected to the rear end portion of the front bearing forming portion 67 and covering the front plate portion 31 are provided.

  The front casing main body 71 is connected to the rear end portion of the front bearing forming portion 67, the front facing portion 72 facing the front plate portion 31, and the front main body cylindrical portion 75 connected to the outer edge portion of the front facing portion 72. Have

  The inner peripheral surface 68 of the front bearing forming portion 67 and the inner surface 73 of the front facing portion 72 are connected via a front case body tapered surface 74. The outer peripheral surface 22 of the inlet cylinder part 21 and the inner peripheral surface 68 of the front bearing formation part 67 are opposed to each other through a gap Gc1. The front surface 32 of the front side plate portion 31 and the inner surface 73 of the front surface facing portion 72 are opposed to each other through the gap Ga1. The outer peripheral surface 22 of the inlet cylinder part 21 and the front case main body taper surface 74 of the front facing part 72 are opposed to each other through a gap Ga1. The inner surface of the expanded diameter pipe portion 65 and the circular arc surface 23 of the inlet tube portion 21 are opposed to each other through the gap Gb1. The inner peripheral surface 76 of the front main body cylinder portion 75 and the outer peripheral surface of the front side plate portion 31 are opposed to each other through a gap Gr.

  The pump rear casing 81 is connected to the rear end portion of the front casing main body portion 71, connected to the rear casing main body portion 91 covering the rear side plate portion 41 and the rear casing main body portion 91, and arranged around the shaft portion 51. The rear bearing forming portion 82 and the rear wall plate portion 85 connected to the rear end portion of the rear bearing forming portion 82 and facing the shaft portion 51 are provided.

  The rear casing main body 91 includes a rear main body cylindrical portion 92 connected to the rear end portion of the front casing main body portion 71 and a rear surface facing portion that is connected to the rear end portion of the rear main body cylindrical portion 92 and faces the rear side plate portion 41. 95.

  The rear surface 42 of the rear plate portion 41 and the inner surface 96 of the rear surface facing portion 95 are opposed to each other through the gap Ga2. The outer peripheral surface 52 of the shaft portion 51 and the inner peripheral surface 83 of the rear bearing forming portion 82 are opposed to each other through a gap Gc2. The inner surface 86 of the rear wall plate portion 85 and the rear end surface 53 of the shaft portion 51 are opposed to each other through the gap Gb2.

  The pump drive device 200 includes a motor 210 having an output shaft 211, a cup 220, a plurality of drive magnets 219 fixed to the cup 220, and a drive device casing 230 that covers the motor 210 and the cup 220.

  The cup 220 is made of carbon steel and functions as a yoke for the drive magnet 219. The cup 220 includes a cup cylindrical part 221 and a motor connecting part 225 connected to the cup cylindrical part 221. The output shaft 211 of the motor 210 is fixed to the motor connection portion 225. A plurality of drive magnets 219 are fixed to the cup cylindrical portion 221. The drive magnet 219 is a permanent magnet and is an Nd (neodymium) magnet.

  The drive device casing 230 includes a casing main body 231 and a cap 241 connected to the casing main body 231. The casing main body 231 has a casing cylindrical portion 232 and a casing bottom portion 235 connected to the casing cylindrical portion 232. The motor 210 is disposed inside the casing main body 231 and is fixed to the casing bottom 235.

  The cap 241 includes a pump fitting portion 242 into which the rear bearing forming portion 82 and the rear wall plate portion 85 are fitted, a pump receiving portion 244 connected to the pump fitting portion 242, and a pump receiving portion 244. And an engaging portion 246 that engages with an opening edge portion of the casing main body 231.

  Next, the operation of the pump 100 will be described. When the motor 210 operates and the output shaft 211 rotates, the cup 220 and the plurality of drive magnets 219 rotate. When the drive magnet 219 rotates, the driven magnet 19 that is magnetically coupled to the drive magnet 219 rotates about the rotation axis AX together with the drive magnet 219. When the drive magnet 219 rotates, the impeller 10 rotates around the rotation axis AX inside the pump casing 60 together with the driven magnet 19.

  When the impeller 10 rotates, the working liquid is sucked into the pump casing 60 from the suction port 6. The working liquid sucked into the pump casing 60 flows from the impeller inlet 12 into the impeller internal flow path Pr of the impeller 10. The working liquid that has flowed into the impeller internal flow path Pr receives centrifugal force from the rotating blades 11, flows out of the impeller outlet 13, and is then discharged from the discharge port 7.

  A part of the working liquid flowing out from the impeller outlet 13 flows into the inner surface 73 of the front facing portion 72 and the gap Ga1 between the front case main body tapered surface 74 and the front surface 32 of the front side plate portion 31. The working liquid that has flowed into the gap Ga1 flows through the gap Gc1 between the inner peripheral surface 68 of the front bearing forming portion 67 and the outer peripheral surface 22 of the inlet tube portion 21, and then is defined by the inner surface 66 of the enlarged diameter pipe portion 65. Flows through Gb1. The working liquid in the gap Gb1 flows from the impeller inlet 12 into the impeller internal flow path Pr.

  Further, the other part of the working liquid flowing out from the impeller outlet 13 flows into the gap Ga <b> 2 between the inner surface 96 of the rear surface facing portion 95 and the rear surface 42 of the rear side plate portion 41. The working liquid that has flowed into the gap Ga2 flows through the gap Gc2 between the inner peripheral surface 83 of the rear bearing forming portion 82 and the outer peripheral surface 52 of the shaft portion 51, and then the inner surface 86 of the rear wall plate portion 85 and the rear of the shaft portion 51. It flows through the gap Gb2 with the end surface 53. The working liquid in the gap Gb2 flows into the impeller internal flow path Pr through the through hole 56.

  The outer peripheral surface 22 and the inner peripheral surface 68 are parallel. Further, the outer peripheral surface 22 and the inner peripheral surface 68 are circular in a plane orthogonal to the rotation axis AX. The outer peripheral surface 22 and the inner peripheral surface 68 are liquid bearing surfaces, and the liquid bearing 1 </ b> A is formed between the outer peripheral surface 22 and the inner peripheral surface 68. A gap Gc1 between the outer peripheral surface 22 and the inner peripheral surface 68 is the bearing gap 2. The working liquid flowing in the bearing gap 2 between the outer peripheral surface 22 and the inner peripheral surface 68 functions as a lubricating liquid for the liquid bearing 1A.

  The outer peripheral surface 52 and the inner peripheral surface 83 are parallel. In addition, the outer peripheral surface 52 and the inner peripheral surface 83 are circular in a plane orthogonal to the rotation axis AX. The outer peripheral surface 52 and the inner peripheral surface 83 are liquid bearing surfaces, and the liquid bearing 1 </ b> B is formed between the outer peripheral surface 52 and the inner peripheral surface 83. A gap Gc <b> 2 between the outer peripheral surface 52 and the inner peripheral surface 83 is the bearing gap 2. The working liquid flowing in the bearing gap 2 between the outer peripheral surface 52 and the inner peripheral surface 83 functions as a lubricating liquid for the liquid bearing 1B.

  In the present embodiment, the contact between the impeller 10 and the pump casing 60 is suppressed and the impeller 10 is supported in a non-contact manner by the pump casing 60 even under conditions where the hydrodynamic bearing is not established in the liquid bearings 1A and 1B. The liquid bearings 1A and 1B are optimized. Hereinafter, the optimized liquid bearing 1A will be described. The liquid bearing 1B is also optimized in the same manner as the liquid bearing 1A.

  FIG. 2 is a schematic diagram showing the liquid bearing 1A. 1 A of liquid bearings have the impeller 10 which has the outer peripheral surface 22 which is an outer surface arrange | positioned around the rotating shaft AX, and the pump casing 60 arrange | positioned around the impeller 10. FIG. The impeller 10 and the pump casing 60 are relatively rotatable. The impeller 10 is a first member that functions as a rotor, and the pump casing 60 is a second member that functions as a stator.

  The pump casing 60 has a bearing gap between the inner peripheral surface 68 that is the first inner surface that forms the bearing gap 2 with the outer peripheral surface 22 and the outer peripheral surface 22 on the inlet side of the bearing gap 2 into which the lubricating liquid flows. The first dimension between the inner surface 73 that is the second inner surface that forms the gap Ga1 of the second dimension Id that is larger than the first dimension Cd of 2, and the outer peripheral surface 22 on the outlet side of the bearing gap 2 from which the lubricating liquid flows out. And an inner surface 66 that is a third inner surface that forms a gap Gb1 having a third dimension Od larger than Cd. The gap Ga1 is an inlet-side flow path connected to the inlet of the bearing gap 2, and the gap Gb1 is an outlet-side flow path connected to the outlet of the bearing gap 2.

  The working liquid of the pump 1 is used as the lubricating liquid flowing through the bearing gap 2. As the working liquid, a working liquid having a viscosity of 1 [cP] to 5 [cP] at an air temperature of 20 [° C.] is used. Water may be used as the working liquid. The viscosity of water at an air temperature of 20 [° C.] is 1.002 [cP].

  The pressure Pa in the gap Ga1 is higher than the pressure Pb in the gap Gb1 so that the lubricating liquid flows in the axial direction parallel to the rotation axis AX in the bearing gap 2. Lubricating liquid (working liquid) with increased pressure flows from the impeller outlet 13 into the gap Ga1, and the pressure Pa of the gap Ga1 becomes higher than the pressure Pb of the gap Gb1. Further, since the second dimension Id of the gap Ga1 is larger than the first dimension Cd of the bearing gap 2, the pressure Pa of the gap Ga1 can be increased.

  The outer peripheral surface 22 has a circular cross section, and the inner peripheral surface 68 is a cylindrical surface. FIG. 2 shows a state in which the rotation axis AX of the inlet cylinder portion 21 of the impeller 10 and the center axis BX of the front bearing forming portion 67 of the pump casing 60 coincide with each other. Moreover, the inlet cylinder part 21 which forms the bearing clearance 2 between the inner peripheral surface 68 is a straight member having a constant diameter.

When the first dimension of the bearing gap 2 is Cd and the diameter of the inlet cylindrical portion 21 of the impeller 10 is d,
0.002 ≦ Cd / d ≦ 0.02 (1)
Satisfy the conditions.

  In the state shown in FIG. 2, the rotation axis AX and the center axis BX coincide with each other, and the first dimension Cd of the bearing gap 2 around the outer peripheral surface 22 is constant. As shown in FIG. 2, the pressure gradient of the bearing gap 2 from the inlet side to the outlet side is uniform in the circumferential direction of the outer peripheral surface 22.

  FIG. 3 is a schematic diagram showing the operation of the impeller 10. When the impeller 10 moves in the radial direction with respect to the pump casing 60 in a state where the pressure Pa is larger than the pressure Pb and the lubricating liquid flows in the axial direction in the bearing gap 2, the impeller 10 is returned to the original position. A resilience to return is generated.

  For example, as shown in FIG. 3, when the impeller 10 moves upward and the center axis BX of the pump casing 60 and the rotation axis AX of the impeller 10 are shifted, the first bearing gap 2 on the upper side of the impeller 10 is changed. The one dimension Cd is smaller than the first dimension Cd of the bearing gap 2 on the lower side of the impeller 10. As a result, the flow rate of the lubricating liquid in the lower bearing gap 2 of the impeller 10 is increased, and the pressure of the upper bearing gap 2 of the impeller 10 is increased as shown in FIG. Greater than the pressure. When a pressure difference is generated between the upper bearing gap 2 and the lower bearing gap 2 of the impeller 10, a force for moving the impeller 10 downward, that is, an attempt to return the impeller 10 to the original position. A restoring force (a force to make the rotation axis AX coincide with the central axis BX) acts on the impeller 10. Thereby, the first dimension Cd of the bearing gap 2 returns to the original value, and the first dimension Cd of the bearing gap 2 is constant around the outer peripheral surface 22. Therefore, contact between the impeller 10 and the pump casing 60 is suppressed.

  This restoring force is generated even when the rotational speed of the impeller 10 is low. For example, when the diameter d is 25 mm, the first dimension Cd is 0.25 mm, and Cd / d is 0.01, the hydrodynamic bearing is established and the impeller 10 is supported by the pump casing 60 in a non-contact manner. For this, the impeller 10 must be rotated at about 15000 [rpm]. In this embodiment, when Cd / d is 0.01 by providing a pressure difference between the inlet side and the outlet side of the bearing gap 2 and flowing the lubricating liquid in the axial direction of the bearing gap 2, the design point If the impeller 10 is rotated at a rotational speed of about 58%, the impeller 10 can be supported in a non-contact manner by the pump casing 60 by the restoring force described above.

  That is, when a rotor having a certain Cd / d relationship is to be supported in a non-contact manner by the stator, if the restoring force according to this embodiment is used, the rotation speed is less than half that when using a hydrodynamic bearing. You can do it.

  Further, this restoring force is generated even if the first dimension Cd of the bearing gap 2 is large. For example, in order to establish a hydrodynamic bearing in a state where the impeller 10 having a diameter d of 25 [mm] is rotated at a rotational speed of 58% of the design point, conventionally, the first dimension Cd is set to 0.025 [mm]. It is not established unless Cd / d is about 0.001. In the present embodiment, even when the first dimension Cd is 0.25 [mm] when the diameter d is 25 [mm], the pump casing is rotated by rotating the impeller 10 at a rotational speed of 58% of the design point. 60 can support the impeller 10 in a non-contact manner.

  That is, when the rotor having a certain diameter d is to be supported in a non-contact manner by the stator, the first dimension Cd of the bearing gap 2 is reduced by approximately the use of the restoring force according to this embodiment as compared with the case where the dynamic pressure bearing is used. Can be 10 times larger.

  Further, this restoring force is generated independently of the viscosity of the lubricating liquid. When the working liquid of the pump 100 is used as the lubricating liquid, there is a possibility that a situation where it is difficult to establish a dynamic pressure bearing with the viscosity of the lubricating liquid (working liquid) may occur. If the restoring force according to the present embodiment is used, the working liquid can be used as a lubricating liquid regardless of the viscosity of the working liquid.

  FIG. 4 is a diagram showing the results of the evaluation test of the pump 100. As shown in FIG. In the evaluation test, a pump 100 having a rotor (impeller 10) having a diameter d of 25 [mm] and Cd / d of 0.01 and a stator (pump casing 60) was used.

  In the evaluation test, the position of the rotor is measured using a laser displacement meter while the rotor is rotated with respect to the stator while changing the rotational speed of the rotor, the flow rate of the lubricating liquid, and the pressure. It was measured whether or not. FIG. 4 shows the flow rate-head characteristics at each rotational speed of the rotor. The horizontal axis represents the flow rate of the lubricating liquid flowing into the bearing gap 2. The vertical axis represents the head of the pump 100 and corresponds to the pressure difference between the inlet side and the outlet side of the bearing gap 2.

  The flow rate and the head at the design point of the pump 100 are 100 [%]. With the rotational speed at the design point of the pump 100 being 100 [%], the flow rate-head characteristics at each rotational speed when the rotational speed was changed to 78 [%], 68 [%], and 58 [%] were evaluated. .

  In FIG. 4, white circles “◯” indicate operating points where the rotor is supported in a non-contact manner with the stator, and black circles “●” indicate operating points where the rotor contacts the stator.

  The rotational speed 58 [%] is the minimum design rotational speed, and contact between the rotor and the stator was not confirmed at a flow rate of the design point flow rate of 100 [%] or less. On the other hand, when the flow rate increases and the head (pressure difference) decreases, contact between the rotor and the stator is confirmed. Accordingly, it can be confirmed that when the pressure difference between the inlet side and the outlet side becomes small, the axial flow of the lubricating liquid in the bearing gap 2 is weakened, and the above-described restoring force cannot be obtained.

  In addition, at the rotational speeds of 68 [%], 78 [%], and 100 [%], the pressure difference between the inlet side and the outlet side is sufficient, and the dynamic pressure effect is obtained as the rotational speed increases. Therefore, contact between the rotor and the stator was not confirmed.

  Thus, it was confirmed that if the first dimension Cd of the bearing gap 2 is defined so as to satisfy the condition of the expression (1) without depending on the rotational speed of the rotor, a restoring force can be obtained.

  Further, it was confirmed that the same tendency was obtained not only when Cd / d was 0.01 but also when 0.002 and 0.02.

  As described above, according to the present embodiment, a dynamic pressure bearing is not established by providing a pressure difference between the inlet side and the outlet side of the bearing gap 2 and flowing the lubricating liquid in the bearing gap 2 in the axial direction. A restoring force can also be generated under the conditions (rotor speed, bearing gap size, and viscosity of the lubricating liquid), and the contact between the rotor and the stator can be suppressed by the restoring force.

  This restoring force suppresses contact between the rotor and the stator even when the rotor rotation speed is low. Therefore, even when the pump 100 is started up, the rotor rotation speed is lower than a predetermined value even in the first rotation speed range. The contact between the rotor and the stator is suppressed. Also, if the rotational speed of the rotor is in the second rotational speed range higher than a predetermined value, a hydrodynamic bearing is established by the dynamic pressure of the lubricating liquid acting between the rotor and the stator, and the rotor is supported in a non-contact manner by the stator. can do.

  Further, when the restoring force is generated, the first dimension Cd of the bearing gap 2 may be larger than the condition that the dynamic pressure bearing is established, so that high smoothness or high machining accuracy is required on the outer surface of the rotor and the inner surface of the stator. Not. Further, in a general dynamic pressure bearing, a groove may be provided in the rotor, but in this embodiment, the groove is unnecessary. Thereby, the restrictions on processing of the rotor and the stator are eased. Further, since the first dimension Cd may be large, it is possible to prevent the foreign matter from being clogged in the bearing gap 2 even if the foreign matter is mixed in the lubricating liquid.

  Further, according to the present embodiment, the generated pressure of the pump 100 itself is guided to the liquid bearings 1A and 1B, and a static pressure effect is also obtained by using the secondary flow. A resell or land like a conventional hydrostatic bearing is unnecessary. Further, by using the working liquid of the pump 100 as the lubricating liquid of the liquid bearings 1A and 1B, the structure becomes simpler than the structure in which the working liquid supply system and the lubricating liquid supply system are separately provided, and the inlet side flow An external high-pressure pump or piping for obtaining the pressure difference of the lubricating liquid between the passage and the outlet side passage is also unnecessary.

Second Embodiment
A second embodiment will be described. FIG. 5 is a schematic diagram illustrating an example of the pump 300. The pump 100 described in the first embodiment has a configuration in which a rotor (impeller 10) is provided inside a cylindrical stator (pump casing 60). The pump 300 shown in FIG. 5 has a structure in which a cylindrical rotor 500 is provided around the stator 400.

  The pump 300 shown in FIG. 5 is an axial flow pump that conveys a working liquid. The pump 300 includes a stator 400 that is a first member having an outer surface 401 disposed around the rotation axis AX, and a rotor 500 that is a second member disposed around the stator 400. The stator 400 and the rotor 500 have blades. The stator 400 and the rotor 500 are relatively rotatable.

  The rotor 500 is located between the first inner surface 501 that forms the bearing gap 310 with the outer surface 401 and the outer surface 401 on the inlet side of the bearing gap 301 into which the lubricating liquid flows, than the first dimension Cd of the bearing gap 2. A third dimension Od larger than the first dimension Cd is formed between the second inner surface 502 that forms the inlet-side flow path Ga3 having a large second dimension Id and the outer surface 401 on the outlet side of the bearing gap 310 through which the lubricating liquid flows out. And a third inner surface 503 that forms the outlet-side flow path Gb3. The working liquid of the pump 300 is used as the lubricating liquid.

  The pump 300 makes the pressure Pa of the inlet side channel Ga3 higher than the pressure Pb of the outlet side channel Gb3 so that the lubricating liquid flows in the bearing gap 310 in the axial direction parallel to the rotation axis AX.

  In the plane orthogonal to the rotation axis AX, the outer surface 401 and the first inner surface 501 are circular, and when the first dimension of the bearing gap 310 is Cd and the diameter of the stator 400 is d, the condition of the above-described equation (1) is satisfied. Satisfied.

  A magnet 519 is disposed on the rotor 500, and a motor coil 319 is provided outside the housing 360 of the pump 300. When a current flows through the motor coil 319, the rotor 500 having the magnet 519 rotates.

  A magnet 520 is provided at the axial end of the rotor 500, and a magnet 420 is provided at a position facing the magnet 503 in the stator 400. The axial relative position of the rotor 500 with respect to the stator 400 is maintained by the balance of the attractive force or repulsive force between the magnet 520 and the magnet 420.

  Thus, even with the pump 300 of the type in which the rotor 500 is disposed around the stator 400, the contact between the stator 400 and the rotor 500 can be suppressed by the restoring force.

  In each of the above-described embodiments, the pump may be a magnetic coupling pump, a canned motor pump, or a sealless pump.

  1A, 1B Liquid bearing, 2 Bearing gap, 6 Suction port, 7 Discharge port, 9 Discharge hose connection pipe section, 10 Impeller (first member), 11 Blade, 12 Impeller inlet, 13 Impeller exit, 19 Driven magnet , 20 front shroud, 21 inlet cylinder, 22 outer peripheral surface (outer surface), 23 arc surface, 24 inlet tapered surface, 31 front plate portion, 32 front surface, 33 front plate tapered surface, 40 rear shroud, 41 rear plate portion, 42 Rear surface, 43 Rear plate taper surface, 51 shaft portion, 52 outer peripheral surface, 53 rear end portion, 54 arc surface, 55 shaft taper surface, 56 through hole, 60 pump casing (second member), 61 pump front casing, 62 suction Hose connection pipe part, 65 expanded diameter pipe part, 66 inner surface (third inner surface), 67 front bearing forming part, 68 inner peripheral surface (first inner surface), 71 front casing body part, 72 front facing part, 3 inner surface (second inner surface), 74 front case main body taper surface, 75 front main body cylindrical portion, 76 inner peripheral surface, 81 pump rear casing, 82 rear bearing forming portion, 83 inner peripheral surface (first inner surface), 85 rear wall Plate portion, 86 inner surface (third inner surface), 91 rear casing main body portion, 92 rear main body cylinder portion, 95 rear surface facing portion, 96 inner surface (second inner surface), 100 pump, 200 pump driving device, 210 motor, 211 output shaft 219 Driving magnet, 220 cup, 221 cup cylindrical part, 225 motor connecting part, 230 driving device casing, 231 casing main body, 232 casing cylindrical part, 235 casing bottom part, 241 cap, 242 pump fitting part, 244 pump receiving part, 246 engaging part, 300 pump, 310 bearing clearance, 400 stator, 420 magnet, 500 low , 501 First inner surface, 502 Second inner surface, 503 Third inner surface, 519 magnet, 520 magnet, AX rotation axis, BX central axis, Cd first dimension, Id second dimension, Od third dimension, Ga1, Ga2 gap ( Inlet side flow path), Gb1, Gb2 gap (outlet side flow path), Gc1, Gc2 gap, Pr impeller internal flow path.

Claims (3)

A first member having an outer surface disposed around the rotation axis;
A second member disposed around the first member;
With
The first member and the second member are rotatable relative to each other;
The second member is larger than the first dimension of the bearing gap between the first inner surface forming a bearing gap with the outer surface and the outer surface on the inlet side of the bearing gap into which lubricating liquid flows. A third dimension outlet side channel larger than the first dimension between the second inner surface forming the second dimension inlet side channel and the outer surface on the outlet side of the bearing gap through which the lubricating liquid flows out. A third inner surface forming
In the bearing gap, the pressure in the inlet-side flow path is made higher than the pressure in the outlet-side flow path so that the lubricating liquid flows in an axial direction parallel to the rotation axis.
pump. The outer surface and the first inner surface are circular in a plane orthogonal to the rotation axis,
When the first dimension is Cd and the diameter of the first member is d,
0.002 ≦ Cd / d ≦ 0.02
Satisfy the conditions of
The pump according to claim 1. As the lubricating liquid, a working liquid to be transported is used.
The pump according to claim 1 or 2.

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