Pump

Abstract

To provide a pump capable of being stably operated.SOLUTION: The pump includes an impeller and a sliding structure. The impeller has a back-side pressure-receiving surface and a front-side pressure-receiving surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Miniaturization of pumps is expected in a variety of fields, including pharmaceuticals and chemical synthesis. In particular, in recent years, the development of pharmaceutical synthesis flows specialized for small-lot, multi-product production has become popular, and there is a growing demand for compact pumps to be used in manufacturing equipment.

[0003] The liquids transported by pumps (handled liquids) include those that are dangerous if they leak or are expensive. To transport such liquids, pumps with a leak-free structure are required.

[0004] In addition, if the rotating body (i.e., the impeller and rotor) housed in the casing comes into contact with the casing, the rotating body may wear, and the wear of the rotating body may cause the generation of foreign matter. Therefore, it is required to suppress the generation of foreign matter and maintain the cleanliness of the handled liquid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-188591 [Patent Document 2] Japanese Utility Model Application Publication No. 45-69404 [Patent Document 3] Japanese Patent Application Publication No. 48-45904 Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, pumps have a rotating shaft to which an impeller is fixed. The rotating shaft allows the impeller to rotate stably around its center. However, the rotating shaft generates foreign matter such as wear particles due to sliding against its support. As a result, problems such as contamination of the pumped liquid and heat generation can occur. If such problems occur, the pump may not be able to operate stably.

[0007] Patent Document 1 discloses a pump section 1 that rotates an impeller 10 by forming a rotating magnetic field and using the attractive and repulsive forces between a plurality of air-core coils 20 and a plurality of permanent magnets 17 (see paragraph 0028).

[0008] However, in the pump section 1 of Patent Document 1, a strong magnetic force acts between the air-core coil 20 and the permanent magnet 17, causing the impeller 10 to be attracted to the housing 2. As a result, there is a concern that the impeller 10 may rotate while sliding against the housing 2, which may result in the generation of wear powder or damage to the housing 2 due to wear. As a result, there is a risk that the pump section 1 may not be able to operate stably.

[0009] Conversely, if the magnetic force is weak, the rotating impeller 10 may whirl more, making it difficult to increase the rotational speed of the impeller 10. Even in this case, the pump section 1 may not be able to operate stably.

[0010] Therefore, an object of the present invention is to provide a pump that can be operated stably. [Means for solving the problem]

[0011] In one aspect, a pump is provided, comprising: an impeller in which a rotating element is embedded and which rotates by a driving force external to the pump; a pump casing that houses the impeller; and a sliding structure formed between the impeller and the pump casing, wherein the impeller has a back pressure-receiving surface having a first pressure-receiving area and a front pressure-receiving surface having a second pressure-receiving area smaller than the first pressure-receiving area.

[0012] In one aspect, the impeller has a tapered surface that forms a part of the back-side pressure-receiving surface, and the sliding structure is formed between the tapered surface and an opposing surface of the pump casing that faces the tapered surface. In one aspect, the impeller has a front-side housing portion that houses a plurality of blades, and the sliding structure is formed between the front-side housing portion and an opposing surface of the pump casing that faces the front-side housing portion. In one aspect, the impeller has a rear-side housing portion that houses the rotating element, and the sliding structure is formed between the outer peripheral surface of the rear-side housing portion and an opposing surface of the pump casing that faces the outer peripheral surface of the rear-side housing portion.

[0013] In one aspect, the impeller has a convex tapered surface formed in a front-side housing portion that houses a plurality of blades, and the sliding structure is formed between the convex tapered surface and an opposing surface of a pump casing that faces the convex tapered surface. In one aspect, the pump casing has a protrusion extending toward the impeller, the impeller has a protrusion accommodating portion that accommodates the protrusion, and the sliding structure is formed between the protrusion and the protrusion accommodating portion. In one embodiment, the sliding structure includes a plurality of grooves formed in at least one of the impeller and the pump casing.

[0014] In one aspect, the pump casing has a volute chamber formed around the impeller, and the volute chamber is composed of a spiral groove whose cross-sectional area gradually increases from the start of the spiral to the end of the spiral. In one aspect, the volute chamber is composed of a plurality of spiral grooves, including the spiral groove, arranged along the rotation direction of the impeller, and the pump casing has a confluence chamber connected to the volute chamber. In one embodiment, at least one of the pump casing and the impeller is made of a resin having slidability. In one embodiment, the pump casing has a convex portion extending from the surface of a flat opposing surface formed on the casing body toward the rear-side housing portion of the impeller. [Effects of the Invention]

[0015] The impeller has a rear pressure-receiving surface and a front pressure-receiving surface that has a smaller pressure-receiving area than the rear pressure-receiving surface. A pump equipped with such an impeller can operate stably. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 illustrates an embodiment of a pump. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] 10A and 10B are diagrams showing an embodiment of a back pressure-receiving surface and a front pressure-receiving surface formed on an impeller. [Figure 4] 10A and 10B are diagrams showing another embodiment of the sliding structure. [Figure 5] 10A and 10B are diagrams showing another embodiment of the sliding structure. [Figure 6] FIG. 6 is a cross-sectional view taken along line BB in FIG. 5. [Figure 7] FIG. 6 is a cross-sectional view taken along line CC in FIG. 5. [Figure 8] FIG. 10 is a diagram showing another embodiment of the volute chamber. [Figure 9] 10A and 10B are diagrams showing another embodiment of the sliding structure. [Figure 10] 10A and 10B show another embodiment of the pump. [Figure 11] 10A and 10B show another embodiment of the pump. [Figure 12] 10A and 10B show another embodiment of the pump. [Figure 13] 10A and 10B show another embodiment of the pump. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] Fig. 1 is a diagram showing one embodiment of a pump. As shown in Fig. 1, the pump 1 includes an impeller 10 in which a permanent magnet 30 serving as a rotating element is embedded and which rotates by a driving force from outside the pump 1 (in this embodiment, the action of a rotating magnetic field), a pump casing 20 that houses the impeller 10, and a sliding structure SS formed between the impeller 10 and the pump casing 20. Details of the sliding structure SS will be described later.

[0019] The impeller 10 has a plurality of blades 13, a front housing portion 10a that houses the plurality of blades 13, and a rear housing portion 10b that houses a permanent magnet 30. In this embodiment, the front housing portion 10a and the rear housing portion 10b are integrally molded members. In another embodiment, the front housing portion 10a and the rear housing portion 10b may be made of different members.

[0020] The pump casing 20 has a casing body 21 that houses the impeller 10, and a suction port 22 and a discharge port 23 connected to the casing body 21. The suction port 22 has a suction opening 20a, and the discharge port 23 has a discharge opening 20b.

[0021] The suction port 22 and the discharge port 23 are arranged perpendicular to each other. More specifically, the suction port 22 extends along the axis CL of the pump 1, and the discharge port 23 extends perpendicular to the axis CL. A pump 1 having this structure is called an end-top pump.

[0022] The permanent magnet 30 is disposed on the back side of the plurality of blades 13 in the direction of the axis CL. In other words, the permanent magnet 30 is disposed outside the flow path of the liquid (handled liquid) transported by the pump 1. Outside the pump 1, a power source 100 for rotating the impeller 10 is disposed adjacent to the permanent magnet 30.

[0023] Here, "the rear side of the plurality of blades 13" refers to the area on the rear side housing portion 10b side that faces the convex opposing surface 50 of the pump casing 20. The permanent magnet 30 is arranged in an area that is located "closer to the rear side of the plurality of blades 13" than the area in which the volute chamber 15 of the pump casing 20 is arranged.

[0024] The power source 100 is not particularly limited as long as it has a configuration that rotates the impeller 10. In this embodiment, the power source 100 is configured to apply a rotating magnetic field to the permanent magnet 30 when power is supplied. In one embodiment, the power source 100 may be a device that electrically generates a magnetic field.

[0025] In this embodiment, the pump 1 is equipped with a permanent magnet 30 as a rotating element that rotates the impeller 10. In one embodiment, depending on the type of power source 100, the pump 1 does not necessarily need to be equipped with a permanent magnet 30. An example of a rotating element that rotates the impeller 10 is a material that is excited by an external magnetic field, such as a coil or a steel plate.

[0026] When driven, the power source 100 forms a rotating magnetic field between itself and the permanent magnet 30, causing the impeller 10 in which the permanent magnet 30 is embedded to rotate. When the impeller 10 rotates, liquid (more specifically, the pumped liquid) is introduced into the impeller 10 through the suction port 20a. The power source 100 is configured to operate when the pump casing 20 is filled with liquid.

[0027] The impeller 10 has a liquid inlet 12 extending along the axis CL of the pump 1. The liquid inlet 12 is connected to the suction port 20a. A plurality of blades 13 are arranged at equal intervals around the liquid inlet 12. Liquid introduced into the impeller 10 through the liquid inlet 12 is discharged radially outward from the impeller 10 by the rotating blades 13. The rotating blades 13 impart velocity energy to the liquid.

[0028] Figure 2 is a cross-sectional view taken along line AA in Figure 1. As shown in Figure 2, pump casing 20 has a volute chamber 15 formed around impeller 10. Volute chamber 15 is composed of a single spiral groove 60 whose cross-sectional area gradually increases from the spiral start portion to the spiral end portion.

[0029] The spiral groove 60 has a starting end 60a with the smallest cross-sectional area and a terminal end 60b with the largest cross-sectional area. The cross-sectional area of ​​the spiral groove 60 gradually increases from the starting end 60a to the terminal end 60b. The terminal end 60b communicates with the discharge outlet 20b through the discharge port 23.

[0030] The liquid discharged from the impeller 10 is introduced into the starting end 60a of the spiral groove 60 and flows through the volute chamber 15 formed by the spiral groove 60. The velocity energy imparted to the liquid is converted into pressure energy as it passes through the volute chamber 15. The pressurized liquid is then discharged from the terminal end 60b of the spiral groove 60 and transported to the outside through the discharge port 20b.

[0031] Fig. 3 is a diagram showing one embodiment of a rear pressure-receiving surface and a front pressure-receiving surface formed on an impeller. As shown in Fig. 3, the impeller 10 has a rear pressure-receiving surface PR1 having a first pressure-receiving area (see the solid arrow in Fig. 3) and a front pressure-receiving surface PR2 having a second pressure-receiving area (see the dotted arrow in Fig. 3) that is smaller than the first pressure-receiving area.

[0032] The liquid passing through the volute chamber 15 fills the space between the front-side housing portion 10a and the casing main body 21 and the space between the rear-side housing portion 10b and the casing main body 21. The liquid filling these spaces has the same pressure, but the rear-side pressure-receiving surface PR1 and the front-side pressure-receiving surface PR2 have different pressure-receiving areas.

[0033] The rear pressure-receiving surface PR1 and the front pressure-receiving surface PR2 are subjected to the pressure of the liquid discharged from the impeller 10, while the rear pressure-receiving surface PR1 has a larger area than the front pressure-receiving surface PR2. Therefore, the force of the liquid acting on the impeller 10 acts more strongly on the rear pressure-receiving surface PR1 than on the front pressure-receiving surface PR2.

[0034] As a result, the impeller 10 is attracted toward the power source 100 by the magnetic force acting between the permanent magnet 30 disposed inside the impeller 10 and the power source 100, while the impeller 10 moves toward the suction side against the magnetic force acting between the permanent magnet 30 and the power source 100.

[0035] According to this embodiment, even if a magnetic force acts between the permanent magnet 30 and the power source 100, the impeller 10, which has the rear-side pressure-receiving surface PR1 and the front-side pressure-receiving surface PR2, can maintain its relative position with respect to the pump casing 20 without coming into close contact with the casing main body 21. Therefore, the pump 1 does not need to have a rotating shaft that supports the impeller 10. The pump 1 having this configuration can achieve stable operation without problems such as the generation of foreign matter such as wear powder or heat generation.

[0036] More specifically, the pump 1 in this embodiment can achieve the following effects (A) and (B). Effect (A) is as follows: By balancing the levitation force generated in the sliding structure SS on the rear pressure-receiving surface PR1 and the load due to the magnetic force in the external rotating magnetic field, contact between the impeller 10 and the pump casing 20 is suppressed (effect (A)).

[0037] The effect (B) is as follows: By balancing the load acting on each of the rear pressure-receiving surface PR1 and the front pressure-receiving surface PR2 with the load due to the magnetic force in the external rotating magnetic field, the load acting on the sliding structure SS is reduced, and the levitation force acting on the sliding structure SS suppresses contact between the impeller 10 and the pump casing 20 (effect (B)).

[0038] The impeller 10 (more specifically, the rear housing portion 10b) has a concave tapered surface 40 that forms part of the rear pressure-receiving surface PR1. The concave tapered surface 40 is an inclined surface that gradually slopes toward the center of the impeller 10 from the surface of the rear housing portion 10b toward the front housing portion 10a.

[0039] The pump casing 20 has a convex opposing surface 50 that faces the concave tapered surface 40 of the impeller 10. The convex opposing surface 50 has a shape that corresponds to the concave tapered surface 40, and more specifically, is an inclined surface that gradually protrudes from the surface of the casing body 21 toward the back-side housing portion 10b of the impeller 10.

[0040] 1 to 3, the sliding structure SS is disposed between the power source 100 and the permanent magnet 30, and is formed between the concave tapered surface 40 and the convex opposing surface 50. More specifically, the sliding structure SS has at least one of a sliding surface SS1 formed on the concave tapered surface 40 and a sliding surface SSa formed on the convex opposing surface 50.

[0041] When the space between the impeller 10 and the casing body 21 is filled with liquid and the impeller 10 rotates, dynamic pressure of the liquid is generated between the sliding surface SS1 of the impeller 10 and the sliding surface SSa of the pump casing 20. The impeller 10 is supported without contact by the dynamic pressure of the liquid.

[0042] In order to generate dynamic pressure of the liquid more actively, the sliding structure SS may have a plurality of grooves formed in at least one of the impeller 10 (i.e., the sliding surface SS1) and the pump casing 20 (i.e., the sliding surface SSa). In this embodiment, the sliding structure SS has a plurality of grooves formed in the sliding surface SS1 (see the hatched areas in FIGS. 1 and 3).

[0043] The shape of the grooves is not particularly limited as long as they can generate dynamic pressure in the liquid. In one embodiment, the grooves may be spiral grooves extending radially outward from the center of the impeller 10, or may be grooves extending linearly in a radial direction.

[0044] The sliding structure SS has a tapered structure with a concave tapered surface 40 and a convex opposing surface 50. The sliding structure SS having such a structure can suppress not only the movement of the impeller 10 in the direction of the axis CL (i.e., the axial direction) but also the movement in a direction perpendicular to the direction of the axis CL (i.e., the radial direction) by the load (attractive force, repulsive force) of the impeller 10 only in the direction of the axis CL. Therefore, the impeller 10 can maintain a predetermined posture without whirling even during rotation.

[0045] The impeller 10 has a through hole 11 formed in its central portion and extending along the axis CL. The through hole 11 connects the space between the concave tapered surface 40 and the convex opposing surface 50 with the liquid inlet 12. Therefore, liquid that has flowed between the concave tapered surface 40 and the convex opposing surface 50 passes through the through hole 11 and returns to the liquid inlet 12.

[0046] Furthermore, in this embodiment, by arranging the permanent magnet 30 on the rear side of the impeller 10, the power source 100 that transmits power to the permanent magnet 30 can be arranged away from the liquid flow path. This arrangement allows the size of the impeller 10 to be reduced.

[0047] If the power source 100 were to be placed on the liquid flow path side (i.e., on the front side where the multiple blades 13 are arranged), the size of the impeller 10 in the radial direction would need to be increased in order to place the power source 100 away from the suction port 20a. However, in this case, the peripheral speed of the impeller 10 would increase, which could result in the impeller 10 whirling significantly. To prevent such whirling, the magnetic force acting between the power source 100 and the permanent magnet 30 needs to be increased.

[0048] However, increasing the magnetic force increases the load (attractive and repulsive forces) on the impeller 10 in the direction of the axis CL, which may make it difficult to maintain the relative position of the impeller 10 with respect to the pump casing 20. In this case, for example, in order to maintain the relative position of the impeller 10, the precision of the grooves formed in the sliding structure SS must be increased (for example, grooves on the order of 10 μm must be formed). This type of work is generally difficult to perform, and it is also difficult to use a resin material.

[0049] According to this embodiment, the permanent magnet 30 is disposed on the rear side of the impeller 10. Therefore, the size of the impeller 10 can be reduced, and as a result, the pump 1 can achieve stable operation. By reducing the size of the permanent magnet 30, the mass of the impeller 10 itself can also be reduced, and the small permanent magnet 30 can contribute to achieving stable operation of the pump 1.

[0050] In one embodiment, at least one of the pump casing 20 and the impeller 10 is made of a resin having slidable properties (e.g., PTFE). Preferably, the entire pump 1 is made of resin.

[0051] When the pump 1 is started, the magnetic force acting between the impeller 10 and the power source 100 causes the impeller 10 to contact the casing main body 21. Therefore, in order to ensure the sliding characteristics of the impeller 10 relative to the pump casing 20 when the pump 1 is started, the pump 1 is preferably made of a resin (e.g., PTFE) that has excellent sliding properties.

[0052] According to this embodiment, by achieving the above-described effects (A) and (B), a large levitation force is not required. Therefore, there is no need to strictly control the gaps between the components of the pump 1, and the manufacturing process of the pump 1 can be simplified. As a result, the pump 1 can be made of resin.

[0053] For example, in this embodiment, the pump 1 does not have a sliding structure between the front housing portion 10a and the casing main body 21. Therefore, there is no need to strictly control the gap between the front housing portion 10a and the casing main body 21. As a result, there is no need to precisely machine the components of the pump 1, and the pump 1 can be made of resin without any problems.

[0054] Furthermore, the pump 1 equipped with the tapered sliding structure SS does not require strict control of the gap of the sliding structure SS. Therefore, the components of the pump 1 do not need to be precisely machined, and the pump 1 can be made of resin without any problems.

[0055] Fig. 4 is a diagram showing another embodiment of the sliding structure. In the embodiment shown in Fig. 4, the pump 1 has a sliding structure SS formed between the outer peripheral surface of the rear housing portion 10b and the casing main body 21, and a sliding structure SS formed between the front housing portion 10a and the casing main body 21.

[0056] More specifically, the sliding structure SS has a sliding surface SS2 formed on the outer peripheral surface of the rear accommodating portion 10b, and a sliding surface SSb formed on the opposing surface of the casing main body 21 that faces the outer peripheral surface of the rear accommodating portion 10b. Furthermore, the sliding structure SS has a sliding surface SS3 formed on the front accommodating portion 10a, and a sliding surface SSc formed on the opposing surface of the casing main body 21 that faces the front accommodating portion 10a.

[0057] 4, the sliding structure SS may have not only tapered sliding surfaces SS1 and SSa formed on the concave tapered surface 40 and the convex opposing surface 50, but also sliding surfaces SS2 and SSb formed in a direction perpendicular to the axis CL (radial direction) and sliding surfaces SS3 and SSc formed in the axis CL direction (axial direction). In one embodiment, the sliding structure SS may have at least one of the sliding surfaces SS2 and SSb and the sliding surfaces SS3 and SSc.

[0058] In this embodiment, the sliding structure SS may also have a plurality of grooves formed on at least one of the sliding surfaces SS2, SSb and the sliding surfaces SS3, SSc. In this embodiment, the sliding structure SS has a plurality of grooves formed on the sliding surface SS2 (see the hatched areas in FIG. 4) and a plurality of grooves formed on the sliding surface SS3 (see the hatched areas in FIG. 4).

[0059] The sliding structure SS that constitutes the sliding surfaces SS2 and SSb can support, without contact, the radial load of the rotating impeller 10. Similarly, the sliding structure SS that constitutes the sliding surfaces SS3 and SSc can support, without contact, the axial load of the rotating impeller 10.

[0060] In particular, depending on the operating conditions of the pump 1, if the pressure of the liquid pressurized by the rotation of the impeller 10 increases, the impeller 10 may move to the suction side of the pump 1, causing the front housing portion 10a to come into contact with the casing main body 21. Therefore, in the embodiment shown in Fig. 4, the sliding structure SS that constitutes the sliding surfaces SS3, SSc can support the load of the impeller 10 without contacting it, even if the impeller 10 moves.

[0061] Fig. 5 shows another embodiment of the sliding structure. In the above-described embodiment, the pump casing 20 has the suction port 22 and the discharge port 23 that are perpendicular to each other, but in the embodiment shown in Fig. 5, the pump casing 20 has the suction port 22 and the discharge port 23 that extend in the same direction.

[0062] Figure 6 is a cross-sectional view taken along line BB in Figure 5. As shown in Figure 6, volute chamber 15 is made up of a plurality of spiral grooves 60A, 60B, and 60C that are arranged at equal intervals along the rotation direction of impeller 10. These plurality of spiral grooves 60A, 60B, and 60C have the same shape.

[0063] Spiral groove 60A has a starting end 60Aa with the smallest cross-sectional area and a terminal end 60Ab with the largest cross-sectional area. Spiral groove 60B has a starting end 60Ba with the smallest cross-sectional area and a terminal end 60Bb with the largest cross-sectional area. Spiral groove 60C has a starting end 60Ca with the smallest cross-sectional area and a terminal end 60Cb with the largest cross-sectional area.

[0064] A starting end 60Ba of the spiral groove 60B is connected to a terminal end 60Ab of the spiral groove 60A. Similarly, a starting end 60Ca of the spiral groove 60C is connected to a terminal end 60Bb of the spiral groove 60B, and a starting end 60Aa of the spiral groove 60A is connected to a terminal end 60Cb of the spiral groove 60C.

[0065] In this way, spiral grooves 60A to 60C extend continuously and are connected to one another in the rotation direction of impeller 10. Multiple spiral grooves 60A to 60C are evenly arranged so that the pressure of the liquid flowing through volute chamber 15 is uniform throughout volute chamber 15.

[0066] With this arrangement, the pump 1 can reduce pressure fluctuations in the liquid per rotation of the impeller 10. As a result, the impeller 10 can more reliably maintain its relative position with respect to the pump casing 20.

[0067] Figure 7 is a cross-sectional view taken along line CC in Figure 5. As shown in Figure 7, pump casing 20 has confluence chamber 16 connected to volute chamber 15. Confluence chamber 16 is an annular flow path and is connected to discharge port 20b. Therefore, the liquid flowing through volute chamber 15 (more specifically, spiral grooves 60A to 60C) is introduced into confluence chamber 16 and then transferred to the outside through discharge port 20b.

[0068] Fig. 8 is a diagram showing another embodiment of the volute chamber. As shown in Fig. 8, the volute chamber 15 is composed of a plurality of spiral grooves 60A, 60B arranged at equal intervals along the rotation direction of the impeller 10. These spiral grooves 60A, 60B have the same shape. In this way, the volute chamber 15 may be composed of two spiral grooves 60A, 60B. The number of spiral grooves 60 is not particularly limited. In one embodiment, four or more spiral grooves 60 may be arranged.

[0069] Fig. 9 is a diagram showing another embodiment of the sliding structure. In the embodiment shown in Fig. 9, the impeller 10 has a flat surface 80 formed in the rear housing portion 10b and forming a part of the rear pressure-receiving surface PR1. The pump casing 20 has a flat opposing surface 90 formed in the casing body 21 and opposing the flat surface 80.

[0070] The sliding structure SS has at least one of a sliding surface SS4 formed on the flat surface 80 and a sliding surface SSd formed on the flat opposing surface 90. Furthermore, in the embodiment shown in Fig. 9, the sliding structure SS has at least one of a sliding surface SS2 and a sliding surface SSb.

[0071] In the above-described embodiment, the sliding structure SS has at least one of the sliding surface SS1 formed on the concave tapered surface 40 and the sliding surface SSa formed on the convex opposing surface 50 (see, for example, FIG. 1), but the sliding structure SS may also have flat sliding surfaces SS2 and SSb formed in the radial direction and flat sliding surfaces SS4 and SSd formed in the axial direction.

[0072] Fig. 10 shows another embodiment of the pump. In the embodiment shown in Fig. 10, the impeller 10 has a convex tapered surface 110 formed in the front housing portion 10a. The pump casing 20 has a concave opposing surface 120 that faces the convex tapered surface 110. The convex tapered surface 110 protrudes from the front housing portion 10a toward the liquid inlet 12, and the concave opposing surface 120 has a shape that corresponds to the convex tapered surface 110.

[0073] The sliding structure SS is formed between the convex tapered surface 110 and the concave opposing surface 120. More specifically, the sliding structure SS has at least one of a sliding surface SS5 formed on the convex tapered surface 110 and a sliding surface SSe formed on the concave opposing surface 120.

[0074] In the above-described embodiment, the power source 100 is disposed adjacent to the permanent magnet 30 along the direction of the axis CL, but in the embodiment shown in Fig. 10, the power source 100 is disposed adjacent to the permanent magnet 30 along a direction perpendicular to the direction of the axis CL. In other words, the power source 100 is disposed radially outward of the impeller 10 so as to surround the impeller 10 (more specifically, the permanent magnet 30).

[0075] In one embodiment, even in the embodiment shown in Fig. 10, the power source 100 may be disposed adjacent to the permanent magnet 30 along the direction of the axis CL. Also in the embodiments described above (see Figs. 1 to 9), the power source 100 may be disposed adjacent to the permanent magnet 30 along a direction perpendicular to the direction of the axis CL.

[0076] In this embodiment as well, the force of the liquid acting on the impeller 10 is greater on the rear pressure-receiving surface PR1 than on the front pressure-receiving surface PR2. As a result, the impeller 10 moves toward the suction side against the magnetic force acting between the permanent magnet 30 and the power source 100.

[0077] The sliding structure SS has a convex tapered surface 110 and a concave opposing surface 120. Therefore, the sliding structure SS can suppress not only the movement of the impeller 10 in the direction of the axis CL but also the movement in a direction perpendicular to the direction of the axis CL, by the load on the impeller 10 only in the direction of the axis CL.

[0078] Fig. 11 shows another embodiment of the pump. In the embodiment shown in Fig. 11, the pump casing 20 has a protrusion 140 extending from the surface of the flat opposing surface 90 toward the rear housing portion 10b. The protrusion 140 extends along the axis CL and is arranged concentrically with the impeller 10.

[0079] The impeller 10 has a protrusion accommodating portion 130 that accommodates the protrusion 140. The protrusion accommodating portion 130 has a size necessary to accommodate the protrusion 140. The through hole 11 is connected to the protrusion accommodating portion 130.

[0080] The sliding structure SS is formed between the protrusion 140 and the protrusion accommodating portion 130. More specifically, the sliding structure SS has at least one of a sliding surface SSf formed on the protrusion 140 and a sliding surface SS6 formed on the protrusion accommodating portion 130.

[0081] In the above-described embodiment (see, for example, FIG. 9), the sliding structure SS is configured to support the rotating impeller 10 in a non-contact manner on the outer periphery side of the impeller 10, but in this embodiment, the sliding structure SS is configured to support the rotating impeller 10 in a non-contact manner on the inner periphery side of the impeller 10. With this configuration, the pump 1 can more effectively prevent the rotating impeller 10 from whirling.

[0082] 12 is a diagram showing another embodiment of the pump. In the above-described embodiment, the pump 1 includes an impeller 10 having a concave tapered surface 40 and a pump casing 20 having a convex opposing surface 50.

[0083] In one embodiment, the pump 1 may include an impeller 10 having a convex tapered surface 240 and a pump casing 20 having a concave opposing surface 250. Even with this configuration, the pump 1 can achieve the same effects as those described above (more specifically, effect (A) and effect (B)). The concave tapered surface 40 and the convex tapered surface 240 may be collectively referred to simply as tapered surfaces.

[0084] Fig. 13 is a diagram showing another embodiment of the pump. In the embodiment shown in Fig. 13, the pump 1 has the same structure as the pump 1 described with reference to Fig. 10, and the power source 100 is arranged adjacent to the permanent magnet 30 along the axis CL.

[0085] In this case, the impeller 10 is attracted toward the power source 100 by the magnetic force acting between the permanent magnet 30 arranged inside the impeller 10 and the power source 100, while the impeller 10 moves toward the suction side against the magnetic force acting between the permanent magnet 30 and the power source 100.

[0086] Therefore, when the pump 1 starts, the magnetic force of the power source 100 causes the impeller 10 to approach the back side (i.e., the power source 100 side). Thereafter, when the pump 1 is operating, the impeller 10 moves to the suction side against the magnetic force acting between the permanent magnet 30 and the power source 100. When the impeller 10 rotates at this time, sliding of the impeller 10 against the pump casing 20 may cause foreign matter to be generated.

[0087] 13, the pump casing 20 has a protrusion 300 that extends from the surface of the flat opposing surface 90 toward the rear housing portion 10b. When the pump 1 starts, the protrusion 300 contacts the rear housing portion 10b of the impeller 10. In particular, the protrusion 300 faces the center of the rear housing portion 10b where the peripheral speed of the impeller 10 is slow.

[0088] This configuration reduces the contact area between the impeller 10 and the pump casing 20. Therefore, even when the impeller 10 rotates, the generation of foreign matter due to sliding between the impeller 10 and the pump casing 20 can be prevented.

[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 pump 10 impeller 10a Front storage section 10b Rear side storage section 11 Through holes 12 Liquid inlet 13 wings 15 Volute chamber 16 Meeting room 20 Pump casing 20a Intake port 20b Discharge port 21 Casing body 22 Suction port 23 Discharge port 30 Permanent Magnets 40 Concave tapered surface 50 Convex opposing surface 60,60A,60B,60C spiral groove 60a,60Aa,60Ba,60Ca Starting end 60b,60Ab,60Bb,60Cb Termination part 80 flat surface 90 flat opposing surface 100 power source 110 Convex tapered surface 120 Concave opposing surface 130 Protrusion housing 140 Protrusion 240 Convex tapered surface 250 Concave opposing surface 300 convex part SS sliding structure SS1,SS2,SS3,SS4,SS5,SS6 Sliding surface SSa,SSb,SSc,SSd,SSe,SSf Sliding surface CL axis PR1 Rear pressure receiving surface PR2 Front side pressure receiving surface

Claims

1. A pump, an impeller in which a rotating element is embedded and which rotates by a driving force from outside the pump; a pump casing that houses the impeller; a sliding structure formed between the impeller and the pump casing, The impeller is a rear pressure receiving surface having a first pressure receiving area; a front pressure-receiving surface having a second pressure-receiving area smaller than the first pressure-receiving area.

2. the impeller has a tapered surface that forms a part of the back surface, The pump according to claim 1 , wherein the sliding structure is formed between the tapered surface and an opposing surface of the pump casing that faces the tapered surface.

3. The impeller has a front housing portion that houses a plurality of blades, The pump according to claim 1 , wherein the sliding structure is formed between the front housing portion and an opposing surface of the pump casing that faces the front housing portion.

4. The impeller has a rear side housing portion that houses the rotating element, The pump according to claim 1 , wherein the sliding structure is formed between an outer circumferential surface of the rear housing portion and an opposing surface of the pump casing that faces the outer circumferential surface of the rear housing portion.

5. The impeller has a convex tapered surface formed in a front housing portion that houses a plurality of blades, The pump according to claim 1 , wherein the sliding structure is formed between the convexly tapered surface and an opposing surface of a pump casing that faces the convexly tapered surface.

6. The pump casing has a protrusion extending toward the impeller, The impeller has a protrusion accommodating portion that accommodates the protrusion, The pump according to claim 1 , wherein the sliding structure is formed between the protrusion and the protrusion accommodating portion.

7. The pump of claim 1 , wherein the sliding structure comprises a plurality of grooves formed in at least one of the impeller and the pump casing.

8. the pump casing has a volute chamber formed around the impeller, 2. The pump according to claim 1, wherein the volute chamber is formed of a spiral groove whose cross-sectional area gradually increases from the spiral start portion to the spiral end portion.

9. the volute chamber is composed of a plurality of spiral grooves, including the spiral groove, arranged along the rotation direction of the impeller, 9. The pump according to claim 8, wherein the pump casing has a confluence chamber connected to the volute chamber.

10. The pump according to claim 1 , wherein at least one of the pump casing and the impeller is made of a resin having slidable properties.

11. 2. The pump according to claim 1, wherein the pump casing has a convex portion extending from a flat opposing surface formed on the casing body toward the rear-side housing portion of the impeller.

Images