GB2488219A

GB2488219A - Pump with inlet flow through rotating bearing

Info

Publication number: GB2488219A
Application number: GB1202414.7A
Authority: GB
Inventors: Noriaki Matsunaga; Hiroki Aso
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2011-02-21
Filing date: 2012-02-10
Publication date: 2012-08-22
Anticipated expiration: 2032-02-10
Also published as: JP5631236B2; GB201202414D0; GB2488219B; JP2012172565A

Abstract

An impeller pump has an effective length of a blade of an impeller extended by a central bearing 18 which rotates with the impeller and has fluid guiding holes 18-1C or vanes (see figures 9, 12). The bearing 18 is at least partially made from a magnetic material, and is attracted to magnet part 201 to maintain adequate thrust against thrust bearing 28, thereby minimising backflow from a discharge outlet to a suction inlet. The magnet part 201 may be ring-shaped and may be an electromagnet. It may be controlled according to speed, to provide no thrust at start up, to reduce friction loading. Attraction may be increased at low speeds to reduce backflow, but reduced at higher speeds when the hydrodynamic thrust experienced by the rotor ensures adequate sealing.

Description

DESCRIPTION

PUMP AND HEAT PUMP APPARATUS

S CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority from Japanese Patent Application No. 2011-034185, filed in Japan on February 21, 2011, the content of which is incorporated herein by reference in its entirely

Technical Field

[000!] This invention relates to a pump that conveys a liquid and to a heat pump apparatus including the pump.

Background Art

[0002] Fig. 15 is a sectional view of a conventional pump (Fig. 2 olPatent Literature 1) used in a heat pump apparatus. This pump includes a stator part 17, a rotor part 2!, a pump part 26, and a shaft 27. A lower end portion of the shaft 27 is fixed to a lower casing is, and an upper end portion of the shaft 27 is fixed to a shaft support portion 35 of an upper casing 24, both in a non-rotatable manner. The rotor part 21 rotates freely around the shaft 27. The rotor part 21 includes a magnet part 20 at the outer circumference thereof, and a bearing 18 at the inner circumference, and the magnet part and the bearing 18 are coupled together by a coupling member 19 made of a thermoplastic resin or the like. The coupling member 19 also forms a lower blade plate 25b. A plurality of blades 25e, arranged radially from the center in a circular arc or an involute curve, are placed between an upper blade plate 25a and the lower blade * 2 plate 25b, thereby forming an impeller 25. Rotation of the impeller 25 produces centriftigal force which acts on a liquid and causes the liquid to be pumped from a suction inlet 22 to a discharge outlet 23.

[0003] The shaft support portion 35 has the shape of a plurality of legs arranged in an inverted cone, and is configured to hold the positions of the shaft 27 and a thrust washer 23 which receives thrust force. The shaft support portion 35 is fitted into a suction opening 36 of the upper blade plate 25a.

[0004] The stator part 17 includes an iron core 10 formed of a plurality of stacked electromagnetic steel sheets, a winding 11 wound through a slot (not shown) of the iron core 10 via an insulator 12 (an insulating material), a circuit board 13 connected with a lead wire 14, and the lower easing 15 which is approximately pot-shaped. The circuit board 13 is positioned near one side of the stator part 17 opposite from the pump part.

The rotor part 21 is housed in a hollow portion of the approximately pot-shaped lower casing 15. A shaft hole iSa into which the shaft is fitted is' formed at a center portion of the hollow portion of the lower casing 15.

Citation List Patent Literature [0005) Patent Literature 1: iF 200,8-2 15738 A

Disclosure of Invention

Technical Problem [0006) (Effective length of blades) in the conventional pump used in the heat pump apparatus (Patent Literature 1), the shaft support portion 35 has the shape of a plurality of legs arranged in an * 3 inverted cone. The shaft support portion 35 is fitted into the suction opening 36 of the upper blade plate 25a in order to hold the positions of the shaft 27 and the thrust washer 28 which receives thrust force. That is, the center portion of the impeller 25 has art opening, namely the suction opening 36, which has approximately the same radius as the suction inlet 22. For this reason, the liquid pumping capacity of the pump is reduced by the capacity of this portion (the suction opening 36). This means that an effectivc lcngth of the blades 25c is shortened by the length of the radius of the suction opening 36. This has been a problem, preventing the improvement of the efficiency of the pump.

[0007] (Thrust force) The suction opening 36 of the upper blade plate 25a has approximately the same radius as the radius of the suction inlet 22 (the suction opening 36 and the suction inlet 22 have approximately the same inside radius), so that the upper blade plate 25a has a smaller surface area than the lower blade plate 25b. This leads to a pressure difference between the upper and lower blade plates of the impeller 25, generating thrust force. Consequently, this thrust force increases friction loss of the thrust bearing due to sliding movements and also increases wear of the thrust bearing, resulting in problems of low efficiency of the pump and short longevity of the pump.

[0008] (Backflow) Because there is a gap between the upper blade plate 25a and the upper casing 24, there has been a problem that some of the liquid pumped outwardly by the impeller is not directed to the discharge outlet 23, but flows back to the suction inlet 22, thereby reducing the efficiency of the pump.

[00093 it is an object of this invention to provide a highly efficient and long-life pump and heat pump apparatus by extending the effective length of the blades toward the inside radius of the suction inlet, reducing the friction loss of the thrust bearing, and preventing the backflow of the liquid to the suction inlet.

Solution to Froblein [0010] A pump according to this invention is a pump that includes a suction inlet for drawing in a liquid and a discharge outlet for discharging the liquid drawn in, wherein a suction direction and a discharge direction of the liquid are approximately perpendicular to each other, and the pump includes: a shaft positioned downstream of the suction inlet such that a longitudinal direction of the shaft is approximately same as the suction direction; an impeller configured in a disk shape that rotates around an axis of rotation located in the shaft, the impeller having a plurality of blades formed radially in a radial direction from a center area located at a center portion of the disk shape as seen in the suction direction, the plurality ofblades being positioned at a longitudinal position approximately same as a longitudinal position of the discharge outlet when a longitudinal direction is defined in terms of the longitudinal direction of the shaft, and the impeller being configured to rotate around the axis of rotation located in the shaft, thereby causing the liquid to be drawn in from the suction inlet and discharged from the discharge outlet; a bearing that receives the shaft and is positioned at the center area of the impeller, the bearing having a guide portion guiding the liquid drawn in from the suction inlet to the discharge outlet, and at least a part of the bearing being formed of a material containing a magnetic material; and a magnet part positioned in an upward direction from the bearing to the sUction inlet in an area around an outer circumference of the suction inlet, the magnet part attracting, by magnetic force and in the upward direction, the bearing formed of the material containing the magnetic material.

Advantageous Effects of invention [0011] According to this invention, a bearing is attracted by magnetic attraction force, so that backflow from a discharge outlet to a suction inlet can be prevented.

Brief Description of Drawings

The present invention will become fully understood from the detailed description given hereinafter in conjtmction with the accompanying drawings, in which: [00 123 Fig. 1 is a diagram showing a usage model of a pump 110 according to a first embodiment; Fig. 2 is a sectional view of the pump 110 according to the first embodiment; Fig. 3 is a diagram illustrating an impeller 25 according to the first embodiment; Fig. 4 is a plan view of a suction inlet 22 according to the first embodiment, as seen in an X direction; Fig. 5 is a perspective view of a bearing (18-1) according to the first embodiment; Fig. 6 shows a plan view and a front view of the bearing (18-1) according to the first embodiment; Fig. 7 is a plan view of the bearing (18-1) according to the first embodiment; Fig. 8 shows sectional views of.the bearing (18-1) according to the first embodiment, taken on line 13-B and line C-C; Fig. 9 is a sectional view of a pump 120 according to a second embodiment; Fig. 10 is a perspective view of a bearing (18-2) according to the second embodiment; Fig. 11 is a plan view of the bearing (18-2) according to the second embodiment; Fig. 12 is a sectional view of a pump 130 according to a third embodiment; Fig. 13 is a perspective view of an upper bearing (1 8-3a) according to the third embodiment; Fig. 14 shows a plan view and a sectional view of the upper bearing (18-3a) according to the third embodiment; and Fig. 15 is a diagram showing conventional art.

Description of Embodiments

In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of the present invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve a similar result.

[0013) First embodiment Referring to Figs. 1 to 8, a pump 110 of a first embodiment will be described.

Fig. lisa diagram showing a usage model of the pump 110 of the first embodiment. As shown in Fig. 1, the pump 110 is used, for example, in a heat pump apparatus.

Fig. 2 is a sectional view (a longitudinal sectional view) of the pump 110.

Fig. 3 is a diagram illustrating an impeller 25. In Fig. 3, (a) is a schematic view of blades 25c of the impeller 25 as seen in an X direction (a suction direction of a * 7 liquid) of Fig. 2. un Fig. 3, (b) shows a section A-A of (a) of Fig. 3.

Fig. 4 is a diagram showing a configuration example of a shaft hole 24a of an upper casing as seen in the X direction of Fig. 2. In Fig. 4, the shaft hole 24a of the upper casing has a shape with fOur legs (24a-l), but this is an example. The shaft hole 24a may be configured in any shape that allows the shaft 27 to be fitted therein and that does not offer great resistance to the liquid to be drawn in.

Fig. 5 is a perspective view of a bearing (18-1) of the pump 110.

Fig. 6 shows plan view (as seen in the X direction) and a front view of the bearing (18-1).

Fig. 7 is a diagram showing the plan view of Fig. 6 ((a) of Fig. 6) with through holes (18-ic) indicated by dashed lines.

Fig. 8 shows a section B-B and a section C-C of(b) of Fig. 6.

[0014] (Heatpumpapparatus 100) As shown in Fig. 1, the heat pump apparatus 100 is configured with a compressor 1 that compresses a refrigerant, heat exchangers 3a and 3b, and so on. The heat pump apparatus 100 includes a refrigerant circuit 5 through which a refrigerant 9 flows. For example, the heat exchanger 3a is a radiator. The heat exchanger 3a, a heat utilization device 101 that utilizes hot water heated by the heat exchanger 3a, and the pump [10 are connected with pipes, thereby forming a liquid circuit 4 through which a liquid 8 flows. Examples of the heat utilization device 101 include a tank for storing a liquid and an external heating element such as a floor heating panel.

[0015] (configuration of the pump 110) The pump 110 is configured such that the bearing (18-1) rotates with a rotor part 21.

[001 6J Referring to Fig. 2, a configuration of the pump 110 will be described. The pump 110 includes a stator part 17, the rotor part 21, a pump part 26, the shaft 27, and a suction-side magnet part 201 (magnet part). The suction-side magnet part 201. is a magnet positioned around a suction inlet 22. The shaft 27 is fixed (non-rotatable).

The rotor part 21 rotates around the shaft 27, [0017] (Suction-side magnet part 201) The suction-side magnet part 201 for attracting the bearing (18-1) is positioned around the suction inlet 22 of the upper casing 24. That is, the suction-side magnet part 201 is positioned in an area around an outer circumference of the suction inlet 22.

At least a part of the bearing (IS-I) is formed of a magnetic materiaL That is, the entirety of the bearing (1 8-1) may be formed of the magnetic material. Alternatively, a part of the bearing (18-i) may be formed of the magnetic materiaL For example, only the cylinder portion (18-la) may be formed of the magnetic material. The suction-side magnet part 201 may be of any shape, provided that the shape allows the suction-side magnet part 201 to attract the cylinder portion (18-la) of the bearing (18-1). The cylinder portion (18-la) is cylindrical in shape. Thus, in order to evenly attract an end face of the cylinder portion (18-la), it is ideal that the suction-side magnet part 201 be cylindrical in shape (for example, shaped like a thick washer), and magnetic flux be evenly distributed to respective phases of an end face of the suction-side magnet part 201. The suction-side magnet part 201 may be a permanent magnet or an electromagnet. Fig. 2 shows, the suction-side magnet part 201 made of an electromagnet. in this case, the magnetic force of the suction-side magnet part 201 is controlled by a control device 202 of Fig. 2, depending on the rotational speed of the impeller 25. The control device 202 calculates the rotational speed of the impeller 25 based on the magnetism of the magnet detected by a Hall element 203 embedded in a circuit board 13. This control will be described in detail later in the first embodiment, When the suction-side magnet part 201 is an electromagnet, the magnetic flux can be evenly distributed on the end face by placing a solenoid coil around a cylindrical iron core. The following description will be given assuming that the suction-side magnet part 201 is an electromagnet.

$ [0018] (Stator part 17) (1) A configuration of the stator part 17 will be described. The stator part 17 includes an iron core 10 which is approximately doughnut-shaped and formed of a plurality of stacked electromagnetic steel sheets stamped into a predetermined shape, a winding El wound through a slot (not shown) of the iron core 10 via an insulator 12 (an insulating material), the circuit board 13 connected with a lead wire 14, and a lower casing 15 which is approximately pot-shaped. The circuit board 13 is positioned near one axial end portion of the stator part 17 (at an opposite side from the pump part 26).

(2) The stator part 17, configured with the iron core 10 around which the winding 11 is wound and the circuit board 13, is formed integrally with a molding resin 16. The exterior of the stator part 17 is formed by the molding resin 16.

(3) The stator part 17 and the rotor part 21 constitute, for example, a brushless DC motor.

[00193 (Rotorpart2t) The rotor part 21 is configured with the bearing (18-1), a coupling member 19, and a magnet part 20. The bearing (18-1) is positioned at a center portion of the rotor part 21. The coupling member 19 made of resin is positioned around the bearing (18-1). The magnet part 20 coupled with the bearing (18-1) by the coupling member 19 is positioned around the coupling member 19.

[00203 (Pump part 26) The pump part 26 includes the impeller 25 and the upper casing 24 having the suction inlet 22 and a discharge outlet 23. The liquid circuit 4 is connected with the suction inlet 22 and the discharge outlet 23.

[0021] The rotor part 21 is housed in a hollow portion of the approximately pot-shaped lower casing 15. A shaft hole ISa into which the shaft 27 is fitted is formed at a center portion of the hollow portion of the lower casing 15. The shaft 27 is inserted into the shaft hole 1 Sa in a non-rotatable manner. To achieve this, the shaft 27 to be inserted into the shaft hole 15a has a notched portion in its circular shape.

[0022] The bearing (18-1) of the rotor part 21 is inserted over the shaft 27 fixed to the lower casing 15. A thrust washer 28 is thrther placed on the bearing (18-1) such that an end face (18-Id) of the bearing (18-1) comes into contact with the thrust washer 28, thereby forming a thrust bearing. Then, the end portion of the shaft 27 facing the pump part 26, which protrudes from the thrust washer 28, is inserted into the shaft hole 24a of the upper casing, so as to form the pump part 26 enclosed in the upper and lower casings. The rotor part 21 to which the impeller 25 is fixed is placed around the shaft iS 27 in a freely rotatable naaaner.

[0023] A space enclosed by the lower casing 15 and the upper casing 24 is filled with the liquid of the liquid circuit 4. Thus, the rotor part 21, the impeller 25, the shaft 27, and the thrust washer 28 come into contact with the liquid flowing through the pump 110. The pump 110 is a canned pump in which the liquid flowing through the pump 110 comes into contact with the rotor part 21 ofthebrushless DC motot [0024) The bearing (1 8-1) is configured to pass through a center portion (a center area 25d) of the impeller 25 and protrude from an upper blade plate 25a toward the suction inlet 22.

The bearing (18-1) is formed such that the outer radius of this protruding portion, namely the cylinder portion (18-la), is equivalent to or slightly larger than the S 11 inside radius of the suction inlet 22 and larger than a shaft support portion. The thrust washer 28 is placed in slidable contact with the upper end face (1 8-Id) of the cylinder portion (118-1 a), thereby forming the thrust bearing. The thrust washer 28 is made to contact the end face (18-Id) of the bearing (18-1) so as to be non-rotatable in the rotational direction relative to the upper casing 24. By configuring the thrust bearing in this way, backflow of the liquid to the suction inlet 22 is prevented. Further, a flow path (a guide portion) is prOvided in the bearing (18-1) in order to make the liquid flow from the suction inlet 22 throUgh the impeller 25 to the discharge outlet 23 in a direction approximately perpendicular to the shaft. This flow path is formed, for example, by a plurality of the through holes (18-ic) placed at a longitudinal position corresponding to a longitudinal position of the impeller 25.

A side wall of the cylinder portion (18-la) of the bearing (18-1) is in slidable contact with an edge of a suction opening 36 of the upper blade plate 25a (a region 37 of Fig. 2 indicated by a dashed circle). With this arrangement, the through holes (18-lc) provided in the bearing (18-1) form flow paths continuing from flow paths of the impeller 25. Thus, an effective length of the blades 25c can be extended toward the inside radius of the suction inlet 22.

[0025] As described above, the thrust bearing through which the flow path is provided is formed of the material containing the magnetic material. In the upper casing placed above the thrust bearing, the magnet is placed around the suction inlet so that the bearing is attracted by the magnet. With this arrangement, it is possible to ensure th4t the bearing, the thrust washer, and the upper casing are attached together firmly.

(0026] Conventionally, a shaft support portion 35 of the upper casing 24 is fitted into the hollow portion of the center portion of the impeller 25, thereby making the effective length of the blades 25c shorter. in contrast, the bearing (18-1) that rotates with the rotor part 21 has the through holes (iS-ic) acting as the flow paths directed approximately perpendicularly to the shaft. These flow paths thus function in practically the same manner as the blades 25c, thereby providing the same effect as extending the blades 25c toward the inside radius (a shrouding effect).

[0027] Referring to the drawings, the configuration of the pump 110 will be described in further detail. As shown in Fig. 2, the pump 110 includes the suction inlet 22 through which the liquid is drawn in and the discharge outlet 23 through which the liquid drawn in is discharged. In the pump 110, a suction direction X and a discharge direction Y of the liquid are approximately perpendicular to each other. The pump 110 includes the shaft 27, the irnpeller2S, and the bearing (18-i). The shaft 27is positioned downstream of the suction inlet 22 such that a longitudinal direction of the shaft 27 is approximately the same as the suction direction X. The impeller 25 has the shape of a disk that rotates around the shaft 27. That is, as shown in Fig. 2, the impeller 25 rotates around an axis of rotation 27a located in the shaft 27. As shown in (a) of Fig. 3, the impeller 25 includes a plurality of the blades 25c formed radially in a radial direction from the center area 25d located at a center portion of the disk shape as seen in the suction direction X. [0028] As shown in Fig. 2, the impeller 25 is positioned such that a longitudinal position of the plurality of the blades 25c is approximately the same as a longitudinal position of the discharge outlet 23, the longitudinal direction being defmed in terms of the longitudinal direction of the shaft 27. In the pump 110, the rotor part 21 coupled with the impeller 25 rotates around the shaft 27, thereby causing the liquid to be drawn in through the suction inlet 22 and discharged through the discharge outlet 23. The bearing (18-1) receives the shaft 27. The bearing (18-1) has the guide portion (flow paths) positioned in the center area 25d of the impeller 25. In the bearing (18-1), the guide portion is the through holes (18-ic). The through holes (I 8-Ic) guide the liquid drawn in through the suction inlet 22 to the discharge outlet 23. There are, for example, eight of the through holes (18-Ic) as shown in Figs, 5, 7, 8, and so on.

However, any number of the through holes (18-ic) may be formed. The flow paths may have any sectional shape, and the area thereof may be larger at the outside radius than at the inside radius.

[0029} (Sealing capability) As shown in Fig. 2, the impeller 25 is configured with the upper blade plate 25a, a lower blade plate 25b, and the plurality of the blades 25c. The upper blade plate 25a forms an upper side of the disk-shaped impeller 25. The suction opening 36 ((a) of Fig. 3) is formed at the center portion of the upper blade plate 25a, the suction opening 36 being a circular opening through which the liquid drawn in through the suction inlet 22 is drawn in. The lower blade plate 25b forms a lower side of the disk shape, and is positioned to face the upper blade plate 25a. The plurality of the blades 25c may be formed between the upper blade plate 25a and the lower blade plate 25b.

Alternatively, the blades 25c may be formed integrally with the upper blade plate 25a or the lower blade plate 25b.

As shpwn in Fig. 5, the bearing (18-1) includes the cylinder portion (18-la) and a thick cylinder portion (1 8-Ib) (an example of the guide portion). The cylinder portion (18-Ia) is hollow, and the thick cylinder portion (18-Ib) is hollow, thick-walled, and formed continuously with (under) the cylinder portion (18-la). As shown in Fig. 2, the cylinder portion (18-la) fits into the suction opening 36 of the upper blade plate 25a, and the side wall of the cylinder portion (18-Ia) is in close contact with the edge of the suction opening 36 (the region 37 in Fig. 2). As a means to achieve close contact, welding or the like may be used3 for. example. The thick cylinder portion (18-1 b) has a thick wall thicker than a wall of the cylinder portion (18-la). The plurality of the through holes (18-Ic) are formed in this thick wall so as to be directed approximately perpendicularly to the shaft 27.

In the pump 110, the side wall of the cylinder portion (18-la) is in slidable S contact with the edge of the suction opening 36 (the region 37 in Fig. 2), so that backflow can be prevented.

[0030] (Thrust bearing) As shown in Fig. 2, the pump 110 includes the upper casing 24 in which the suction inlet 22 is formed, and the thrust washer 28 supported by the upper casing 24 so as to be non-rotatable relative to the shaft 27. The bearing (18-1) forms the thrust bearing with the upper end face (18-Id) of the cylinder portion (18-la), the thrust washer 28, and a support portion 24b of the upper casing supporting the thrust washer 28.

[0031] The bearing(l8-l) of the first embodiment is a single-component bearing that functions both in radial and thrust directions, and thus also has the effect of being more dimensionally accurate compared to when the radial and thrust directions are supported by separate bearings.

[0032] (Materials) (1) With regard to materials used in the first embodiment, the upper casing 24, for example, is composed of a hot water-resistant and chemical-resistant thermoplastic resin, such as modified polyphenylene ether (hereinafter m-PPE), polyphenylene sulfide (hereinafter PPS), or syndiotactic polystyrene (hereinafter SPS).

(2) The coupling member 19 and the impeller 25 (the upper blade plate 25a, the lower blade plate 25b, and the blades 25c) are also composed of a resin such as m-PPE, PPS, orSPS.

(3) For the lower casing 15, a metal such as aluminum, stainless steel, or copper may also be used in place of a resin such as m-PPE, PPS, or SPS.

(4) The shaft 27 is composed of stainless steel, ceramic, or the like.

(5) The magnet part 20 is composed of a plastic magnet part made of one type or a mixture of a plurality of types of magnetic particles selected from the group consisting of ferrite particles, neodymium particles, samarium-iron-nitrogen particles, and so on, mixed with a binder resin such as polyamide or PPS.

(6) The bearing (1 8-1) is composed of a material obtained by mixing a highly slidable and wear-resistant thermoplastic resin such as PPS containing carbon fiber or fluororesin, with one type or a mixture of a plurality of types of magnetic particles selected from the group consisting of ferrite particles, neodymium particles, samarium-iron-nitrogen particles, and so on.

(7) The coupling member 19 (including the lower blade plate 25b) may be formed integrally with the bearing (18-1) from the same material. In that case, the material is preferably a highly formable and slidable resin, namely PPS containing carbon fiber or fluororesin, (8) The thrust washer 28 is áomposed of ceramic or stainless steel, and may also be composed of PPS containing carbon fiber or fluororesin.

(9) It is preferable to use a different material, instead of the same material, for each component of the bearing to be in slidable cOntact with another component of the bearing, thereby precluding the possibility of scoring.

[0033) (Control of the suction-side magnet part 201 by the control device 202) As shown in Fig. 2, the suction-side magnet part 201 (electromagnet) for attracting the bearing (18-I) formed of the material containing the magnetic material is positioned around the suction inlet 22 of the upper casing 24. The control device 202 controls the strength of the magnetic force of the suction-side magnet part 201 based on the rotational speed of the impeller 25. As described above, the control device 202 calculates the rotational speed of the impeller 25 based on the value detected by the Hall element 203.

(1) For example, at start-up of the pump, the control device 202 controls the magnetic force of the suction-side magnet part 201 to be zero, This is to avoid affecting start-up performance of the pump. Then, the control device 202 gradually increases the magnetic force of the suction-side magnet part 201.

(2) As the rotational speed of the impeller 25 increases, a difference between suction and discharge pressures increases, thereby increasing thrust force. In such a case, the control device 202 may adjust the magnetic force by changing the quantity of electricity (voltage, current) supplied to the coil of the suction-side magnet part 201 in order to prevent thrust loss from being increased.

(3) Alternatively, the control device 202 may gradually increase the magnetic force from zero when the impeller 25 starts rotating, and decrease the magnetic force when the rotational speed of the impeller 25 exceeds a predetermined speed.

j0034] The configuration of the pump 110 of the first embodiment described above reduces the friction loss of the thrust bearing, extends the effective length of the blades toward the inside radius of the suction inlet 22, and prevents the backflow of the liquid to the suction inlet 22. As a result, a highly efficient and long-life pump and heat pump apparatus can be provided.

[0035] As described above, the bearing (18-1) that forms the flow paths at the center area of the impeller 25 flowing from the suction inlet 22 to the outer periphery of the impeller 25 is formed of the material containing the magnetic material. The bearing (18-1) is attracted by the suction-side magnet part 201 positioned around the suction inlet 22 of the upper casing 24, so that the thrust bearing is attached together firmly.

With this arrangement, the backflow from the discharge outlet to the suction inlet can be prevented. By forming the suction-side magnet part 201 by an electromagnet, the magnetic force can be controlled to be zero at start-up of the pump such that friction loss of the thrust bearing is prevented from being increased due to. magnetic attraction force. When the magnetic force of the suction-side magnet part 201 (electromagnet) is zero, the rotor part 21 and the impeller 25 are pulled downward by gravitational force, and the thrust bearing is not attached together firmly. However, as the rotational speed of the impeller 25 increases, the difference in pressure between the fluid drawn in and the fluid discharged increases. As a result, the thrust force pushing up the impeller 25 in an axial direction increases, thereby causing the thrust bearing to be attached together firmly. If the magnetic attraction force works between the suction-side magnet part 201 and the bearing (18-1) in this state, the friction loss increases. For this reason, the magnetic force is controlled depending on the rotational speed of the impeller 25, such that the magnetic force decreases while the impeller 25 is rotating at a high speed, and so on. Ideally, it is preferred that the control device 202 control the electricity (current, voltage) supplied to the suction-side magnet part 201 such that "(Gravitational force) (thrust force due to the difference between suction and discharge pressures) + magnetic attraction force".

[0036] Second embodiment A second embodiment differs from the first embodiment in the configuration of the bearing. A bearing (18-2) of the second embodiment is configured such that flow paths are formed by a plurality of blades (l8c-2) in contrast to the plurality of the through holes of the bearing (18-1) of the first embodiment. Other than this, the second embodiment is the same as the first embodiment. Thus, as with the first S 18 embodiment, the bearing (18-2) rotates with the rotor part 21.

[0037] Referring to Figs. 9 and 10, a pump 120 of the second embodiment will be described.

Fig. 9 is a sectional view of the pump 120 of the second embodiment.

S Fig. 10 is a perspective view of the bearing (18-2). The bearing (18-2) includes the plurality of the blades (1 8c-2) as the guide portion for guiding the liquid drawn in through the suction inlet 22 to the discharge outlet 23.

Fig. 11 is a plan view of the bearing (18-2) (as seen in the X direction).

[0038] As shown in Fig. 9, the pump 120 includes the suction-side magnet part 201, the control device 202, and the Hall element 203 as in the first embodiment. At least a part of the bearing (18-2) to be described later together with Fig. 10 is formed of a magnetic material as with the bearing (18-1) of the first embodiment. As shown in Fig. 10, for example, only an upper portion (18-2-1) including blades (18c-2) may be formed of the material containing the magnetic material. Alternatively, the entirety of the bearing (18-2), that is the upper portion (1 8-2-1) and a lower portion (18-2-2), may be formed of the material containing the magnetic material. The control device 202 controls the suction-side magnet part 201 in the same way as in the first embodiment.

[0039] As shown in Fig. 10, the bearing (18-2) includes the plurality of the blades (1 8c-2) forming flow paths for passing the liquid from the suction inlet 22 through the impeller 25 to the discharge outlet 23 in a direction approximately perpendicular to the shaft. This has an equivalent effect as the bearing (IS-i) of the first embodiment. In this case, the blades (l8c-2) may be formed to correspond with the blades 25c of the impeller 25. That is, when the blades 25c are formed in a circular are or an involute curve, the blades (18c-2) may be formed based on the same pattern rule (formed to have the same radius of curvature or involute curve). The number of the blades (18c-2) * 19 provided in the bearing (18-2) may be the same as or larger or smaller than the number of the blades 25c of the impeller 25. In other respects, the configuration is the same as that of the first embodiment.

[0040) Third embodiment A pump 130 of a third embodiment will be described. The pump 130 of the third embodiment will be described wherein the bearing (18-2) of the second embodiment is divided into an upper part and a lower part. In the pump 130, the shaft 27 and an upper bearing (18-3a) rotate with the rotor part 21. The impeller 25 is fixed to the rotor part 2!. Thus, as shown in Fig. 12, the impeller 25 rotates around the axis of rotation 27a located in the shaft 27.

[0041) Referring to Figs. 12 to 14, the pump 130 of the third embodiment will be described.

[0042) Fig. 12 is a sectional view of the pump 130 of the third embodiment. As shown in Figs. 12 and 13, in the pump 130, the bearing is divided into two parts, namely the upper bearing (18-3a) and a lower bearing (18-3b). The upper bearing (18-3a) receives one end portion of the shaft 27 at a side facing the suction inlet 22, and includes a plurality of blades (1 8c-3) (Fig. 13) as the guide portion. The lower bearing (1 8-3b) receives the other end portion of the shaft 27 at the opposite side from the suction inlet 22.

[0043J As shown in Fig. 12, the pump 130 includes the suction-side magnet part 201, the control device 202, and the Hafl element 203 as in the first embodiment. As described above, in the pump 130, the bearing is divided into the upper part and the lower part. In the pump 130, the upper bearing (18-3a) shown in Fig. 13 is formed of a material containing a magnetic material. In the third embodiment, the control device 202 controls the suction-side magnet part 201 in the same way as in the first * 20 embodiment.

[00441 Fig. 13 is a perspective view of the upper bearing (18-3a). The upper bearing (18-3a) has the plurality of the blades (l8c-3) as the guide portion.

Fig. 14 shows a front view (as seen in the X direction of Fig. 1) and a sectional view taken on line 0-0.

[0045] (Rotor part 21) As shown in Fig. 12, the magnet part 20 and the shaft 27 are coupled by the coupling member 19. The coupling member 19 also serves as the lower blade plate 25b. These (the magnet part 20, the shaft 27, and the coupling member 19) are fixedly coupled as one unit in both rotational and axial directions. The blades 25c and the upper blade plate 25a are fixedly coupled to the lower blade plate 25b by welding or the like, so as to form one unit. In this way, the magnet part 20, the coupling member 19, the shaft 27, the upper bearing (1 8-3 a), and so on constitute the rotor.

[0046) As shown in Fig. 12, the lower bearing (18-3b) is fitted into the shaft hole 15a of the lower casing 15 so as to be non-rotatable in the rotational direction. A lower end portion of the shaft 27 coupled with the rotor part 21. is inserted into the lower bearing (1 8-3b) in a freely rotatable manner The upper bearing (I 8-3a) is inserted over an upper end portion of the shaft 27 so as to be non-rotatable in the rotational direction relative to the shaft 27. That is, the upper bearing (lS-3a) and the rotor part 21 rotate in unison.

[0047] (Upper bearing (1 8-3a)) As shown in Figs. 1.3 and 14, an upper portion of the upper bearing (18-3a) is shaped like an inverted triangular pamid, and is in slidable contact, in both thrust and radial directions, with the thrust washer 28 outside (under) the radius of the suction inlet 22. Fig. 13 shows how the thrust washer 28is attached to the upper bearing (18-3a). 21 H

The thrust washer 28 is attached to the suction inlet 22 of the upper casing 24 so as to be* non-rotatable in the rotational direction. The thrust washer 28 may be made non-rotatable in the rotational direction, for example as shown in Fig. 13, by cutting away a portion of the circumference thereof to form a notched portion 28-1 and also forming an opposing portion of the upper casing 24 in the same shape (forming a portion opposing the notched portion 28-1 as a protrusion having the same shape). As shown in Fig. 13, the upper portion of the upper bearing (18-Ba) includes the blades (1 Sc-3), having a cross-sectional shape (the same as the shape of the blades (18c-3) shown in (a) of Fig. 14) closely resembling (a shape approximately the same as) the shape of the blades 25c of the impeller 25. The number of the blades and the phase thereof are also made to closely resemble (to be approximately the same as) those of the blades 25c, thereby forming flow paths by the blades (1 8c-3) (the guide portion). In other respects, the configuration is the same as that of the first embodiment.

[0048] The configuration of the third embodiment can also produce the same effect as the first embodiment.

[0049] The pumps 110 to 130 described iii the first to third embodiments have been shown, by way of example, as pumps used for conveying and circulating the liquid in the heat pump apparatus 100, but may also be adaptable to a household pump and so on.

Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the disclosure of this patent specification may be practiced otherwise than as specifically described herein.

List of Reference Sings [0050] 1: compressor * 22 3a, 3b: heat exchangers 4: liquid circuit 5: refrigerant circuit 8: liquid 9: refrigerant 10: iron core 11: winding 12: insulator (insulating material) 13: circuit board 14:leadwire 15: lower casing iSa: shaft hole of the lower casing 16: molding resin 17:statorpart 18-1, 18-2: bearings 18-3 a: upper bearing I 8-3b: lower bearing 18-la: cylinder portion 18-ib: thick cylinder portion 18-ic: througbhole 18-ld: end face 18c-2, 18c-3: blades 19: coupling member 20: magnet part 21:rotorpart 22: suction inlet 23: discharge outlet 24: upper casing 24a: shaft hole 24a-1: leg 24b: support portion 25: impeller 25a: upper blade plate 25b: lower blade plate 25c: blade 25d: center area 26: pump part 27: shaft 27a: axis of rotation 28: thrust washer 30: flow path 35: shaft support portion 36: suction opening 37: region 100: heat pump apparatus 110, 120, 130: pumps 201: suction-side magnet part 202: control device 203: Hall element

Claims

CLAIMS1. A pump including a suction inlet for drawing in a liquid and a discharge outlet for discharging the liquid drawn in, wherein a suction direction and a discharge direction of the liquid are approximately perpendicular to each other, the pump comprising: a shaft positioned downstream of the suction inlet such that a longitudinal direction of the shaft is approximately same as the suction direction; an impeller configured in a disk shape that rotates around an axis of rotation located in the shaft, the impeller having a plurality of blades formed radially in a radial direction from a center area located at a center portion of the disk shape as seen in the suction direction, the plurality of blades being positioned at a longitudinal position approximately same as a longitudinal position of the discharge outlet when a longitudinal direction is defined in terms of the longitudinal direction of the shaft, and the impeller being configured to rotate around the axis of rotation located in the shaft, thereby causing the liquid to be drawn in from the suction inlet and discharged from the discharge outlet; a bearing that receives the shaft and is positioned at the center area of the impeller, the bearing having a guide portion guiding the liquid drawn in from the suction inlet to the discharge outlet, and at least a part of the bearing being formed of a material containing a magnetic material; and a magnet part positioned in an upward direction from the bearing to the suction inlet in an area around an outer circumference of the suction inlet, the magnet part attracting, by magnetic force and in the upward direction, the bearing formed of the material containing the magnetic material.
2. The pump of claim I, wherein the bearing is configured such that at least an upper portion of the bearing facing the suction inlet is formed of the material containing the magnetic material.
3. The pump of claim I or claim 2, wherein the magnet part is an electromagnet that generates magnetic force upon being supplied with electricity.
4. The pump of claim 1, 2 or 3, wherein the magnet part is controlled by a control device such that a strength of the magnetic force is controlled depending on a rotational speed of the impeller.
5. The pump of claim 4, wherein the magnet part is controlled by the control device such that the magnetic force gradually increases from zero when the impeller starts rotating.
6. The pump of claim 5, wherein the magnet part is controlled by the control device such that the magnetic force gradually increases from zero when the impeller starts rotating, and the magnetic force decreases when the rotational speed exceeds a predetermined speed.S
7. The pump of any one of claims ito 6, wherein the impeller includes an upper blade plate forming an upper side of the disk shape and having, at a center portion thereof, a suction opening, the suction opening being a circular opening through which the liquid drawn in from the suction inlet is drawn in, and a lower blade plate forming a lower side of the disk shape and positioned to face the upper blade plate; the plurality of blades are formed between the upper blade plate and the lower blade plate; and the bearing rotates with the impeller and includes a cylinder portion being hollow and configured to fit into the suction opening of the upper blade plate and have a side wall in close contact with an edge of the suction opening.
8. The pump of claim 7, wherein the bearing includes, as the guide portion, a thick cylinder portion formed continuously with the cylinder portion and having a thick wall thicker than a wall of the cylinder portion, the thick cylinder portion having formed in the thick wall a plurality of through holes directed approximately perpendicularly to the shaft.
9. The pump of any one of claims 1 to 8, wherein the bearing includes, as the guide portion, a plurality of blades.
10. The pump of claim 9, wherein the bearing has the plurality of blades shaped in a shape corresponding to a shape of the blades of the impeller.
11. The pump of any one of claims ito 10, wherein the bearing includes an upper bearing configured to receive one end portion of the shaft at a side facing the suction inlet and have the guide portion, and a lower bearing configured to receive an other end of the shaft at a side opposite from the suction inlet, and the upper bearing is formed of the magnetic material.
12. The pump of claim 7 or claim 8, wherein the pump includes an upper casing in which the suction inlet is formed, and a thrust washer supported by the upper casing so as to be non-rotatable relative to the shaft; and the bearing forms a thrust bearing with an upper end face of the cylinder portion, the thrust washer, and a support portion of the upper casing supporting the thrust washer.
13. A pump substantially as hereinbefore described with reference to the accompanying drawings.
14. A heat pump apparatus including the pump of any one of claims 1 to 13.