Pump and pump device

Abstract

To provide a pump capable of resuming operation quickly.SOLUTION: A pump comprises a pump casing. The pump casing has a suction flow path, a discharge flow path arranged above the suction flow path, and a return flow path connected to the highest point of an annular flow path.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pump and a pumping device. [Background technology]

[0002] While a typical centrifugal pump needs to be multi-staged to achieve a low flow rate and a high head, there are also known pumps (e.g., cascade pumps) that have a compact structure that achieves a low flow rate and a high head without being multi-staged.

[0003] Miniaturized pumps are expected to be used in a variety of fields, including pharmaceuticals and chemical synthesis. In particular, in recent years, there has been active development of chemical synthesis flows specialized for small-lot, multi-product production, and it is desirable to incorporate such pumps into chemical synthesis flows. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 50-138406 [Patent Document 2] Japanese Patent Application Publication No. 51-25811 [Patent Document 3] Japanese Unexamined Patent Publication No. 59-103987 Summary of the Invention [Problem to be solved by the invention]

[0005] In such a chemical synthesis flow, there is a risk that the liquid level in the tank storing the chemical will drop to its limit, causing the liquid in the suction pipe connected to the pump to fall. In this case, it is desirable to quickly resume operation of the pump after the liquid level in the tank has returned to normal.

[0006] However, when the pump restarts, there is a risk that gas may be trapped in the suction pipe due to water falling into the suction pipe. In order to efficiently advance the chemical solution synthesis flow, it is desirable to quickly discharge the gas from the pump and quickly restart the pump.

[0007] Therefore, an object of the present invention is to provide a pump and a pump device that can quickly resume operation. [Means for solving the problem]

[0008] In one aspect, a pump is provided that includes a rotating shaft, an impeller attached to the rotating shaft, and a pump casing that houses the impeller and defines an annular passage between the impeller and the pump casing, the pump casing having a suction passage connected to the annular passage, a discharge passage disposed above the suction passage, and a return passage connected to the highest point of the annular passage.

[0009] In one aspect, the suction flow path and the discharge flow path are arranged in a straight line along a direction in which buoyancy of gas contained in the liquid transported by the pump acts. In one aspect, the pump comprises a liquid tank arranged above the pump casing and a sealing member arranged between the pump casing and the liquid tank, the liquid tank having a gas-liquid separation chamber formed throughout the liquid tank and communicating with the discharge flow path and the return flow path, and the sealing member arranged to surround the gas-liquid separation chamber. In one aspect, the pump has an intake port formed in the lower part of the pump casing and communicating with the intake flow path, and an outlet port formed in the upper part of the liquid tank and communicating with the discharge flow path through the gas-liquid separation chamber.

[0010] In one embodiment, the suction flow path is bent midway and connected to the low-pressure side flow path of the annular flow path, and the discharge flow path is bent in a direction symmetrical to the suction flow path and connected to the high-pressure side flow path of the annular flow path. In one embodiment, the pump is a cascade pump, and the impeller has a plurality of radial grooves formed on its periphery.

[0011] In one aspect, a pump device is provided, the pump device comprising the pump described above and a motor that drives the pump.

[0012] In one aspect, the pump device comprises a drive shaft connected to a rotating element of the motor and a magnetic coupling that transmits the rotational force of the drive shaft to the rotating shaft, and the magnetic coupling comprises a motor-side magnet fixed to the drive shaft and a pump-side magnet fixed to the rotating shaft, and the motor-side magnet and the pump-side magnet are arranged in a straight line along a central axis extending parallel to the rotating shaft and the drive shaft. In one aspect, the pump device comprises a coupling case that houses the pump side magnet, a coupling cover that closes the open end of the coupling case, and a detachment prevention pin that prevents the coupling cover from detaching from the coupling case, the detachment prevention pin being inserted into a fastening hole formed in the rotating shaft. In one aspect, the pump device comprises a disk holder fixed to the rotating shaft, a communicating hole formed in the impeller, and a locking pin connected to the disk holder, and the locking pin is inserted into the communicating hole to fix the disk holder to the impeller.

[0013] In one embodiment, the pump device includes a thrust disk accommodated in the accommodation recess of the disk holder, and the thrust disk has a rotation prevention portion formed on its outer circumferential surface. In one aspect, the pump casing includes a casing cover arranged opposite the impeller, and the casing cover has a flow groove that communicates with the communication hole and extends toward the low-pressure side flow path of the annular flow path. In one aspect, the pump device includes a bearing that rotatably supports the rotating shaft, and the bearing has a groove that allows liquid that has flowed into the gap between the rotating shaft and the bearing to pass through. In one aspect, the bearing has a main body portion extending parallel to the rotation axis and a flange portion connected to the main body portion, and the groove has an axial groove formed in the main body portion and a radial groove formed in the flange portion. [Effects of the Invention]

[0014] The pump casing has a structure that quickly discharges gas that has flowed into the pump, allowing the pump to quickly resume operation. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 illustrates an embodiment of a pump. [Figure 2] 2 is a diagram showing a pump device including the pump shown in FIG. 1. FIG. [Figure 3] FIG. 10 is a diagram for explaining the effect of a pump. [Figure 4] 10A and 10B are diagrams showing other embodiments of the inlet and outlet flow paths; [Figure 5] FIG. 10 is a diagram showing a pump as a comparative example. [Figure 6] FIG. 10 is a diagram showing a rotation axis that moves along the central axis direction. [Figure 7] FIG. 10 is a diagram showing a comparative example of a rotation axis inclined relative to the central axis. [Figure 8] 10A and 10B are views showing a coupling case and a coupling cover fixed to a rotating shaft. [Figure 9] FIG. 10 is a diagram showing a disk holder that transmits the rotational force transmitted to the rotating shaft to the impeller. [Figure 10] FIG. 10 is a diagram showing a disk holder that transmits the rotational force transmitted to the rotating shaft to the impeller. [Figure 11] FIG. 10 is a view showing a thrust disk accommodated in an accommodating recess of a disk holder. [Figure 12] FIG. 10 is a view showing a thrust disk accommodated in an accommodating recess of a disk holder. [Figure 13] FIG. 13(a) is a perspective view showing a bearing arranged on the motor side, and FIG. 13(b) is a cross-sectional view taken along line aa in FIG. 13(a). [Figure 14] FIG. 10 is a diagram showing a number of communication holes greater than the number of anti-rotation pins. [Figure 15] 10A and 10B are diagrams showing flow grooves formed in a casing cover. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, identical or corresponding components are designated by the same reference numerals, and duplicated descriptions will be omitted. In the multiple embodiments described below, the configuration of an embodiment that is not particularly described is the same as that of other embodiments, and therefore duplicated descriptions will be omitted.

[0017] Fig. 1 is a diagram showing one embodiment of a pump. Fig. 2 is a diagram showing a pump device including the pump shown in Fig. 1. The pump device PA includes a pump P and a motor M that drives the pump P.

[0018] In this embodiment, the pump P is a self-priming cascade pump that can achieve a small flow rate and a high head. The pump P includes a rotating shaft 2, an impeller 1 attached to the rotating shaft 2, and a pump casing PC that houses the impeller 1 and forms an annular flow passage 13 between the impeller 1 and the pump casing PC.

[0019] The impeller 1 has a disk shape and has a plurality of radial grooves 1a formed on the periphery of the impeller 1. The annular flow passage 13 is arranged to surround these plurality of radial grooves 1a. The pump P as a cascade pump is configured to generate a pressure difference in the annular flow passage 13 that surrounds the impeller 1 by rotating the impeller 1 having the plurality of radial grooves 1a formed therein.

[0020] The pump casing PC includes a casing body 3, an inner casing 4 disposed inside the casing body 3, and a casing cover 30 that closes the open end of the casing body 3. In this embodiment, the casing body 3 and the inner casing 4 are formed as separate members, but they may also be formed as an integrally molded member.

[0021] The pump casing PC has a suction passage 12 connected to the annular passage 13, a discharge passage 14 located above the suction passage 12, and a return passage 20 connected to the highest position (more specifically, the highest position in the vertical direction) of the annular passage 13. In this embodiment, the suction passage 12, the discharge passage 14, and the return passage 20 are formed in both the casing main body 3 and the inner casing 4, respectively.

[0022] 1, the annular passage 13 is formed in the center of the pump casing PC. The suction passage 12 and the discharge passage 14 are arranged in a straight line along the vertical direction and are adjacent to the annular passage 13.

[0023] The suction passage 12 arranged in the lower part of the casing body 3 is bent in the middle and connected to the low-pressure side passage of the annular passage 13. The discharge passage 14 arranged in the upper part of the casing body 3 is bent in the middle and connected to the high-pressure side passage of the annular passage 13.

[0024] The liquid flowing through the suction pipe SP flows into the annular flow path 13 through the suction port 10 and the suction flow path 12. When the impeller 1 rotates, the liquid that has flowed into the annular flow path 13 flows through the annular flow path 13 and is gradually pressurized. The pressurized liquid then flows out of the annular flow path 13 into the discharge flow path 14.

[0025] In this embodiment, the suction flow path 12 and the discharge flow path 14 are adjacent to each other and bent in directions symmetrical to each other in the up-down direction. By bending the suction flow path 12 and the discharge flow path 14 in symmetrical directions, the suction flow path 12 and the discharge flow path 14 are arranged adjacent to each other. As a result, the length of the annular flow path 13 formed between the suction flow path 12 and the discharge flow path 14 can be maximized. By maximizing the length of the flow path, the liquid can be pressurized to the maximum extent.

[0026] As shown in Fig. 1, the pump P includes a liquid tank 5 disposed above a pump casing PC, and a seal member (e.g., an O-ring) S disposed between the pump casing PC and the liquid tank 5. The liquid tank 5 is connected to the upper surface of a casing body 3. The casing body 3 has a seal groove SG formed in its upper surface. The seal member S is fitted into the seal groove SG.

[0027] The liquid tank 5 has a single gas-liquid separation chamber CH formed throughout its entirety and communicating with the discharge flow path 14 and the return flow path 20. When the liquid tank 5 is connected to the casing main body 3, the seal member S is disposed so as to surround the entire gas-liquid separation chamber CH. With this arrangement, the seal member S prevents leakage of the liquid flowing into the gas-liquid separation chamber CH.

[0028] The liquid tank 5 has a wide tank section 5a that communicates with the discharge flow path 14 and the return flow path 20, and a protruding tank section 5b that is located above the wide tank section 5a. The liquid tank 5 has a through-hole 5c that communicates with the wide tank section 5a. In FIG. 1, the through-hole 5c is closed by a priming plug ST. When supplying priming water to the pump P, the operator removes the priming plug ST and supplies priming water to the liquid tank 5 through the through-hole 5c.

[0029] The liquid tank 5 has a discharge port 15 formed in its upper part (more specifically, the protruding tank portion 5b) and connected to the discharge pipe DP. The discharge port 15 communicates with the discharge flow path 14 through the gas-liquid separation chamber CH. Therefore, the liquid flowing out from the annular flow path 13 to the discharge flow path 14 passes through the discharge flow path 14 and is guided to the liquid tank 5.

[0030] During self-priming operation of the pump P, most of the liquid introduced into the liquid tank 5 is transferred to the outside through the discharge port 15 of the liquid tank 5 and the discharge pipe DP. A portion of the liquid is returned to the annular flow path 13 through the return flow path 20 connected to the liquid tank 5.

[0031] In this way, the liquid supplied to the pump P through the suction pipe SP is transferred to the outside through the discharge pipe DP in a pressurized state. However, as mentioned above, there is a risk that the suction pipe SP may become filled with water. In this case, it is desirable to quickly restart the operation of the pump P.

[0032] In order to quickly resume operation of the pump P, it is necessary to quickly discharge gas that has entered the suction pipe SP after water has fallen into the suction pipe SP. In this embodiment, the pump P is configured to quickly discharge gas. The effects of this embodiment will be described below with reference to the drawings.

[0033] Fig. 3 is a diagram illustrating the effects of the pump. In Fig. 3, the structure of the pump P is simplified to clearly illustrate the effects of the pump P. The pump P includes an intake passage 12 and a discharge passage 14 arranged in series along the direction in which the buoyancy of the gas acts. Therefore, the gas contained in the intake pipe SP rises up the intake passage 12 through the intake port 10 and is quickly introduced into the annular passage 13.

[0034] The gas introduced into the low-pressure side passage of the annular passage 13 (i.e., the lower part of the annular passage 13) rises in the annular passage 13 due to its buoyancy and the rotational force of the impeller 1. As described above, the return passage 20 is located at the highest position of the annular passage 13. Therefore, the liquid that has risen in the annular passage 13 is introduced into the liquid tank 5 through the return passage 20 (i.e., without passing through the discharge passage 14). In this case, the return passage 20 functions as a gas passage.

[0035] The gas-liquid separation chamber CH has a liquid chamber LCH formed in the wide tank section 5a and a gas chamber GCH formed in the protruding tank section 5b. The gas chamber GCH is located above the liquid chamber LCH. Therefore, gas introduced into the liquid tank 5 actively moves to the gas chamber GCH due to its buoyancy and is quickly discharged through the discharge port 15.

[0036] According to this embodiment, the pump casing PC has a structure that quickly discharges gas that has flowed into the pump P. Therefore, the pump P can quickly discharge gas and quickly resume normal operation.

[0037] Fig. 4 is a diagram showing another embodiment of the suction flow path and the discharge flow path. In the embodiment shown in Fig. 1, each of the suction flow path 12 and the discharge flow path 14 has a shape bent at a right angle. As shown in Fig. 4, each of the suction flow path 12 and the discharge flow path 14 may have a bent shape so as to be inclined at a predetermined angle (more specifically, an obtuse angle) in order to prevent gas from stagnating.

[0038] In the above-described embodiment, the pump P is a cascade pump. A cascade pump has excellent self-priming properties and is less susceptible to pressure loss on the suction side. Therefore, the pump P can more effectively achieve the effect of quickly discharging gas. To achieve this effect, the pump P does not necessarily have to be a cascade pump. Therefore, the pump P may be a pump other than a cascade pump.

[0039] 5 is a diagram showing a pump as a comparative example. The pump as a comparative example has a suction side (low pressure side) and a discharge side (high pressure side) arranged close to each other. When the suction side and the discharge side are arranged in the same direction, the pump has multiple seal members S1, S2 arranged between the pump casing and the liquid tank.

[0040] Therefore, it is necessary to form a plurality of seal grooves adjacent to each other for arranging the seal members S1 and S2, resulting in a large pump size in its width direction (i.e., horizontal direction).

[0041] 3 and 5, in this embodiment, by arranging the suction flow path 12 and the discharge flow path 14 in a straight line along the vertical direction, the pump P can omit a seal member surrounding the suction flow path 12. As a result, the space required for installing a seal member can be saved, and the size of the pump P can be reduced.

[0042] Furthermore, in this embodiment, the liquid tank 5 has only the gas-liquid separation chamber CH as a discharge-side space that communicates with the discharge flow path 14 and the return flow path 20, and does not have a space (suction-side space) that communicates with the suction flow path 12. If the suction-side space and the discharge-side space were located above the pump casing (see FIG. 5), these spaces would need to be enlarged vertically to obtain the volume necessary to separate the gas and liquid. As a result, the pump would have a large size in its height direction (i.e., vertical direction).

[0043] On the other hand, in this embodiment, by arranging only the gas-liquid separation chamber CH above the pump casing PC, the necessary volume can be obtained without increasing the vertical size of the gas-liquid separation chamber CH. Therefore, the vertical size of the pump P can be reduced. As a result, the pump P can be made more compact.

[0044] Furthermore, according to this embodiment, the gas chamber GCH formed in the protruding tank portion 5b of the liquid tank 5 is positioned higher than the through-hole 5c that communicates with the wide tank portion 5a. Therefore, even when priming water is supplied to the pump P through the through-hole 5c, the level of the priming water does not exceed the liquid chamber LCH, and the gas chamber GCH is filled with gas. This configuration allows the gas-liquid separation chamber CH to separate the liquid and gas more reliably.

[0045] As described above, in order to maximize the pressure of the liquid, it is desirable to maximize the length of the annular flow path 13. According to this embodiment, the distance D1 (see FIG. 3) between the suction flow path 12 and the discharge flow path 14 is shorter than the distance D2 (see FIG. 5) between the flow paths in the pump of the comparative example. In this way, by bringing the suction flow path 12 and the discharge flow path 14 closer to each other, the pressure of the liquid that has flowed into the annular flow path 13 can be maximized. As a result, the pump performance of the pump P can be improved.

[0046] Furthermore, according to this embodiment, by arranging the suction port 10 at the bottom of the pump casing PC, it is not necessary to lay the suction piping SP in a torii-like shape (i.e., torii piping). Therefore, the space (installation space) for installing the pump device PA can be reduced, and the pump device PA can be installed in a narrow space.

[0047] The structure of the pump device PA will be described below with reference to Fig. 2. The pump device PA includes a bracket 40 disposed between the pump casing PC and the motor M, and an inner housing BH disposed between the inner casing 4 and the bracket 40.

[0048] The bracket 40 and the inner housing BH have a cylindrical shape, and are arranged concentrically with the central axis CL of the rotary shaft 2. The inner housing BH is attached to the bracket 40.

[0049] The casing body 3, the inner casing 4, and the inner housing BH are sandwiched between the casing cover 30 and the bracket 40. In this state, the pump device PA is assembled by inserting the positioning pin PP into the casing cover 30, the inner casing 4, the inner housing BH, and the bracket 40.

[0050] The pump device PA includes bearings BR1 and BR2 that rotatably support the rotating shaft 2, a drive shaft MS that is connected to a rotating element RE of the motor M and is arranged in a straight line with the rotating shaft 2 along the direction of the central axis CL, and a magnetic coupling MC that transmits the rotational force of the drive shaft MS to the rotating shaft 2.

[0051] The rotating element RE is a combination of a rotor fixed to the drive shaft MS and a stator surrounding the rotor. Each of the bearings BR1 and BR2 is made of a non-metallic material such as resin. The bearings BR1 and BR2 are, for example, plain bearings. The bearing BR1 is mounted in an inner housing BH, which serves as a stationary member. The bearing BR2 is mounted in a casing cover 30, which also serves as a stationary member.

[0052] The magnetic coupling MC has a motor-side magnet MCa fixed to the drive shaft MS and a pump-side magnet MCb fixed to the rotating shaft 2. The motor-side magnet MCa and the pump-side magnet MCb are arranged in a straight line along the direction of the central axis CL.

[0053] The pump device PA includes a cover plate CP disposed between the motor-side magnet MCa and the pump-side magnet MCb. The cover plate CP is attached to the bracket 40 in a liquid-tight manner and is disposed between the bracket 40 and the inner housing BH. The cover plate CP is made of a non-magnetic material (e.g., resin) that is not affected by the magnetic force generated by the magnetic coupling MC.

[0054] The magnetic coupling MC is configured to generate a magnetic force between the motor-side magnet MCa and the pump-side magnet MCb. Therefore, when the motor-side magnet MCa rotates together with the drive shaft MS due to the driving of the rotating element RE, the magnetic force of the rotating motor-side magnet MCa acts on the pump-side magnet MCb. The magnetic force of the motor-side magnet MCa causes the pump-side magnet MCb to rotate the rotating shaft 2. In this way, the rotating shaft 2 rotates together with the pump-side magnet MCb.

[0055] The flow of liquid sucked into the pump device PA will be described below with reference to Fig. 2. When the impeller 1 rotates together with the rotation of the rotary shaft 2, the liquid flows into the annular flow path 13 through the suction port 10 and the suction flow path 12.

[0056] 2, the inner casing 4 has a through-flow passage 4a extending in the direction of the central axis CL. The through-flow passage 4a is connected to the annular flow passage 13. Therefore, most of the liquid flowing through the annular flow passage 13 flows through the discharge flow passage 14, while a portion of the liquid is introduced into the space on the motor M side through the through-flow passage 4a.

[0057] The inner housing BH has a communication passage BHa that communicates with the bearing BR1 (and the pump-side magnet MCb). The liquid that passes through the through passage 4a is introduced into the communication passage BHa and supplied to the internal space of the inner housing BH. The liquid supplied to the inner housing BH comes into contact with the bearing BR1 attached to the inner housing BH, cooling and lubricating the bearing BR1.

[0058] The motor-side magnet MCa is disposed in a sealed space surrounded by the motor M, the bracket 40, and the cover plate CP. Therefore, the liquid supplied to the internal space of the internal housing BH comes into contact with the cover plate CP, but does not come into contact with the motor-side magnet MCa.

[0059] This configuration eliminates the need for waterproofing the motor-side magnet MCa, while the pump-side magnet MCb is disposed in the internal space of the inner housing BH, making the pump-side magnet MCb waterproof.

[0060] Fig. 6 is a diagram showing the rotating shaft moving along the central axis. As shown in Fig. 6, in this embodiment, the magnetic coupling MC has a motor-side magnet MCa and a pump-side magnet MCb adjacent to each other along the central axis CL. Therefore, the rotating shaft 2 moves along the central axis CL toward the drive shaft MS due to the magnetic force generated between the motor-side magnet MCa and the pump-side magnet MCb.

[0061] Fig. 7 is a diagram showing a comparative example of a rotating shaft that is inclined relative to the central axis. As shown in Fig. 7, the rotating shaft is rotatably supported by a bearing. In Fig. 7, the size of the gap between the rotating shaft and the bearing is exaggerated.

[0062] If a configuration different from the magnetic coupling MC according to this embodiment is used to apply a rotational force to the rotating shaft, the rotating shaft may tilt relative to the bearing. If the rotating shaft is rotated in this state, the rotation of the rotating shaft may cause it to slide against the bearing more than necessary, which may damage the bearing (and / or the rotating shaft).

[0063] According to this embodiment, the rotating shaft 2 and the drive shaft MS are connected by a magnetic coupling MC. Therefore, the rotating shaft 2 is rotatably supported by the bearing BR1 (and bearing BR2) without tilting. In other words, a constant gap can always be formed between the rotating shaft 2 and the bearing BR1 (and bearing BR2). This configuration can prevent damage to the bearings BR1 and BR2 (and / or the rotating shaft 2).

[0064] 8 is a diagram showing the coupling case and coupling cover fixed to the rotating shaft. The pump device PA includes a coupling case CCA that houses the pump-side magnet MCb, a coupling cover CCO that closes the open end of the coupling case CCA, and a detachment prevention pin P that prevents the coupling cover CCO from detaching from the coupling case CCA.

[0065] 8, the coupling case CCA has an outer cylinder portion CCA-1 and an inner cylinder portion CCA-2 that are connected to each other. The outer cylinder portion CCA-1 and the inner cylinder portion CCA-2 extend in the direction of the central axis CL and are arranged concentrically with the rotating shaft 2.

[0066] The inner cylinder portion CCA-2 is disposed radially inward of the outer cylinder portion CCA-1 and extends so as to protrude further toward the impeller 1 than the outer cylinder portion CCA-1. In other words, the length of the inner cylinder portion CCA-2 in the direction of the central axis CL is longer than the length of the outer cylinder portion CCA-1.

[0067] The inner cylindrical portion CCA-2 has an insertion hole CCA-2a extending perpendicular to the direction of the central axis CL. The insertion hole CCA-2a is formed on the tip side of the inner cylindrical portion CCA-2 and communicates with a fastening hole 2a formed in the rotating shaft 2. A separation prevention pin P is inserted into the insertion hole CCA-2a and the fastening hole 2a. The separation prevention pin P is a pin (e.g., a spring pin) configured so that its diameter can be elastically deformed.

[0068] When the coupling cover CCO is closed with the pump-side magnet MCb housed in the coupling case CCA, the insertion hole CCA-2a is exposed, allowing the operator to insert the anti-detachment pin P into the insertion hole CCA-2a and the fastening hole 2a while visually observing the insertion hole CCA-2a (and the fastening hole 2a).

[0069] The separation prevention pin P prevents the coupling cover CCO from separating from the coupling case CCA, and can fix the coupling case CCA (and the pump-side magnet MCb) to the rotating shaft 2.

[0070] 9 and 10 are diagrams showing a disc holder that transmits the rotational force transmitted to the rotating shaft to the impeller. The pump device PA includes a disc holder DH fixed to the rotating shaft 2, a communication hole 50 formed in the impeller 1, and a plurality of anti-rotation pins WP for fastening the disc holder DH to the impeller 1. In one embodiment, at least one anti-rotation pin WP may be provided.

[0071] The disc holder DH is fixed to the rotating shaft 2 by, for example, shrink fitting SF (see FIG. 6). The disc holder DH may also be fixed to the rotating shaft 2 by means of press fitting or the like.

[0072] The disc holder DH has a connecting hole DHa formed in the surface facing the impeller 1. The communicating hole 50 and the connecting hole DHa extend in the direction of the central axis CL. The anti-rotation pin WP is inserted into the connecting hole DHa and the communicating hole 50.

[0073] When the anti-rotation pin WP is inserted, it fixes the disc holder DH to the impeller 1. The disc holder DH is fixed to the rotating shaft 2. Therefore, when the rotating shaft 2 rotates, the rotational force of the rotating shaft 2 is transmitted to the impeller 1 through the disc holder DH.

[0074] According to this embodiment, the anti-rotation pin WP has a structure that connects the disc holder DH and the impeller 1. With this structure, the impeller 1 does not need to have a structure (for example, a protrusion) on either side for connecting to the disc holder DH, and the impeller 1 can have both flat sides.

[0075] Therefore, the size of the gap between the impeller 1 and the inner casing 4 and casing cover 30 arranged on both sides of the impeller 1 can be minimized (see FIG. 2). Since the pump performance depends on the size of this gap, minimizing this gap is important for improving the pump performance. In one embodiment, the impeller 1 may have machined surfaces formed on both sides. In this way, manufacturing the impeller 1 by surface grinding allows for easy dimensional control.

[0076] 11 and 12 are diagrams showing a thrust disk accommodated in the accommodation recess of the disk holder. The pump device PA includes a thrust disk TD accommodated in the accommodation recess RC of the disk holder DH.

[0077] The thrust disk TD is made of, for example, ceramics, etc. The thrust disk TD is held by the disk holder DH and is disposed opposite the bearing BR1 (see FIG. 2), and is configured to rotate together with the disk holder DH.

[0078] The thrust disk TD has a rotation prevention portion TDa that prevents the thrust disk TD from rotating relative to the disk holder DH. The rotation prevention portion TDa is formed on the outer peripheral surface of the thrust disk TD and has a flat shape. The installation recess RC of the disk holder DH has a flat portion DHb, just like the thrust disk TD.

[0079] The thrust disk TD is accommodated in the disk holder DH so that the anti-rotation portion TDa and the flat portion DHb face each other. As a result, the thrust disk TD does not rotate relative to the disk holder DH but rotates integrally with the disk holder DH.

[0080] Fig. 13(a) is a perspective view showing a bearing arranged on the motor side, and Fig. 13(b) is a cross-sectional view taken along line aa in Fig. 13(a). The bearing BR1 has a main body portion BR1a extending parallel to the rotating shaft 2, and a flange portion BR1b connected to the main body portion BR1a.

[0081] The bearing BR1 has grooves BG that allow the passage of liquid that has flowed into the gap between the rotating shaft 2 and the bearing BR1. More specifically, the grooves BG include axial grooves BGa formed on the inner circumferential surface of the main body portion BR1a and radial grooves BGb formed on the surface of the flange portion BR1b that faces the thrust disk TD. These axial grooves BGa and radial grooves BGb are connected to each other. In this embodiment, the bearing BR1 has multiple grooves BG, but it may also have at least one groove BG.

[0082] As described above, the liquid supplied to the inner housing BH cools and lubricates the bearing BR1 mounted in the inner housing BH. By forming the groove BG in the bearing BR1, the liquid can actively pass through the gap between the bearing BR1 and the rotating shaft 2, more efficiently lubricating and cooling the bearing BR1.

[0083] In one embodiment, a groove (not shown) corresponding to the groove BG may be formed on the surface of the thrust disk TD facing the bearing BR1. This configuration allows the liquid to flow more efficiently through the gap between the flange portion BR1b of the bearing BR1 and the thrust disk TD.

[0084] A portion of the liquid flowing through the annular flow passage 13 passes through the gap between the impeller 1 and the casing cover 30 and is introduced into the space in which the bearing BR2 is disposed. This liquid comes into contact with the bearing BR2 to cool and lubricate it. Therefore, in one embodiment, a groove (not shown) corresponding to the groove BG may be formed in the bearing BR2.

[0085] As shown in Figure 2, the inner housing BH is disposed to surround the disc holder DH. Therefore, the liquid that passes through the gap between the flange portion BR1b and the thrust disc TD passes through the gap between the disc holder DH and the inner housing BH. The liquid then passes through the gap between the disc holder DH and the inner casing 4 and is returned to the pump P.

[0086] Fig. 14 is a diagram showing communication holes having a greater number than the number of anti-rotation pins. Fig. 15 is a diagram showing flow grooves formed in a casing cover. In the embodiment shown in Fig. 14, the number of communication holes 50 is greater than the number of anti-rotation pins WP. Therefore, part of the liquid returned to the pump P side passes through communication holes 50 that do not have anti-rotation pins WP inserted therein.

[0087] 15, the casing cover 30 has a communication groove 110 formed on its inner surface 30a. The inner surface 30a of the casing cover 30 faces the impeller 1. The communication groove 110 communicates with the communication hole 50 formed in the impeller 1 and extends toward the low-pressure side flow path of the annular flow path 13.

[0088] Therefore, the liquid that has passed through the communication hole 50 flows through the circulation groove 110 and is returned to the low-pressure side flow path of the annular flow path 13. In this way, by forming the communication hole 50 and the circulation groove 110, a circulation flow of liquid can be created between the motor M side and the pump P side. By creating such a circulation flow, gas remaining in the pump P immediately after starting operation of the pump P and gas that is mixed into the pumped liquid during self-priming operation can be efficiently discharged.

[0089] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0090] 1 impeller 1a Radial groove 2 rotation axes 2a Fastening hole 3 Casing body 4 Inner casing 4a Through-flow channel 5 Liquid tank 5a Wide tank section 5b Projecting tank part 5c through hole 10 Intake port 12 Suction passage 13 Annular flow path 14 Discharge flow path 15 Outlet 20 Return flow path 30 Casing cover 40 Bracket 50 Communication hole 110 Distribution groove P pump Medium motor PA pump device PC pump casing SP suction piping DP discharge piping S sealing material SG seal groove CH gas-liquid separation chamber LCH liquid chamber GCH Gas Chamber ST priming tap S1, S2 sealing material D1,D2 distance BH inner housing BHa communication channel PP Locating Pin BR1,BR2 bearings BR1a main body BR1b flange RE Rotation Element BG Groove BGa axial groove BGb Radial groove CL center axis MS drive shaft MC magnetic coupling MCa motor side magnet MCb pump side magnet CP Cover Plate CCA coupling case CCA-1 outer cylinder CCA-2 inner cylinder part CCA-2a insertion hole CCO Coupling Cover P Anti-detachment pin DH Disc Holder DHa connection hole DHb flat area WP anti-rotation pin SF Shrink Fit RC storage recess TD Thrust Disc TDa Anti-rotation part

Claims

1. A pump, A rotation axis; an impeller attached to the rotating shaft; a pump casing that houses the impeller and forms an annular flow path between the impeller and the pump casing, The pump casing comprises: a suction flow path connected to the annular flow path; a discharge flow path disposed above the suction flow path; a return flow path connected to the highest point of the annular flow path.

2. The pump according to claim 1 , wherein the suction flow path and the discharge flow path are arranged in a straight line along a direction in which buoyancy of gas contained in the liquid transported by the pump acts.

3. The pump a liquid tank disposed above the pump casing; a seal member disposed between the pump casing and the liquid tank, the liquid tank has a gas-liquid separation chamber formed throughout the liquid tank and communicating with the discharge flow path and the return flow path; The pump according to claim 1 , wherein the seal member is disposed so as to surround the gas-liquid separation chamber.

4. The pump a suction port formed in a lower portion of the pump casing and communicating with the suction flow path; 4. The pump according to claim 3, further comprising: a discharge port formed in an upper portion of the liquid tank and communicating with the discharge flow path through the gas-liquid separation chamber.

5. the suction flow path is bent midway and connected to a low-pressure side flow path of the annular flow path, The pump according to claim 1 , wherein the discharge passage is bent in a direction symmetrical to the suction passage and connected to a high-pressure side passage of the annular passage.

6. the pump is a cascade pump; 2. The pump of claim 1, wherein the impeller has a plurality of radial grooves formed in its periphery.

7. 1. A pump device comprising: A pump according to any one of claims 1 to 6; a motor that drives the pump.

8. The pump device a drive shaft connected to a rotating element of the motor; a magnetic coupling that transmits the rotational force of the drive shaft to the rotation shaft, The magnetic coupling is a motor-side magnet fixed to the drive shaft; a pump-side magnet fixed to the rotating shaft, 8. The pump device according to claim 7, wherein the motor-side magnet and the pump-side magnet are arranged in a straight line along a central axis extending parallel to the rotation shaft and the drive shaft.

9. The pump device a coupling case that accommodates the pump-side magnet; a coupling cover that closes an open end of the coupling case; a detachment prevention pin that prevents the coupling cover from being detached from the coupling case, The pump device according to claim 8 , wherein the anti-detachment pin is inserted into a fastening hole formed in the rotating shaft.

10. The pump device a disk holder fixed to the rotating shaft; A communication hole formed in the impeller; a locking pin connected to the disc holder, The pump device according to claim 7 , wherein the anti-rotation pin is inserted into the communication hole to fix the disk holder to the impeller.

11. the pump device includes a thrust disk accommodated in an accommodating recess of the disk holder; 11. The pump device according to claim 10, wherein the thrust disk has a rotation prevention portion formed on an outer circumferential surface thereof.

12. the pump casing includes a casing cover disposed opposite the impeller, The pump device according to claim 10 , wherein the casing cover has a flow groove that communicates with the communication hole and extends toward the low-pressure side flow passage of the annular flow passage.

13. the pump device includes a bearing that rotatably supports the rotary shaft, 8. The pump device according to claim 7, wherein the bearing has a groove that allows passage of liquid that has entered a gap between the rotating shaft and the bearing.

14. The bearing is a main body extending parallel to the rotation axis; a flange portion connected to the main body portion, The groove is an axial groove formed in the body portion; 14. The pump apparatus of claim 13, further comprising a radial groove formed in the flange portion.

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