Contactless centrifugal pump

Abstract

A centrifugal pump for use with a liquid is disclosed. The pump includes a hollow casing arrangement, a rotor and a magnet arrangement. The casing arrangement defines an interior and an intersecting axis, an intake port for receiving said liquid in use and communicating same to said interior and a discharge port communicating with the interior. The rotor is positioned in said interior and rotatable about said axis in spaced relation to said casing. The rotor includes a drive member, a shaft extending axially from the drive member and an impeller coupled to said drive member by said shaft for rotation therewith and adapted to cause fluid from said interior to be ejected through said discharge port upon rotation. The magnet arrangement is disposed outside said interior and is adapted to drive rotation of said drive member about said axis in use through the creation of a rotating magnetic field.

Description

FIELD OF THE INVENTION

This invention relates to the field of centrifugal pumps and in particular to a frictionless or contactless centrifugal pump.

BACKGROUND OF THE INVENTION

Contactless centrifugal pumps are known in the prior art.

One known type of contactless centrifugal pump has a one-piece rotor and impeller including several permanent magnets inside the rotor. About the outer circumference of the casing that surrounds the impeller are two layers (top and bottom) of electromagnets, and a corresponding number of gap detection sensors. The upper layer of electromagnets uses the sensor signals to adjust the repulsion and attraction force of each electromagnet, to set the gap between the rotating rotor and the casing, as well as the vertical position. The lower layer of electromagnets is powered by an alternating current, causing the rotor to rotate. These are driven by a driver, which contains a micro CPU. In the course of stopping, as the rotor decelerates it can be attracted to and touch the electromagnet's core, causing wear. Additionally, this pump is structurally complex, making maintenance relatively difficult for persons other than specialists. Moreover, only relatively small capacity pumps (under 1 KW) of this type are typically made, and this type of pump is relatively expensive when compared to other pumps.

Another known type of contactless centrifugal pump is described in Japanese Patent Publication No. 2005-090478, which is illustrated in FIG. 19 of this disclosure. In this pump, the impeller 40 is directly connected to a metal torque cylinder 41, and is able to rotate within a “can” structure 35. By rotating the magnets on the inside and outside of the can with a motor 37, rotational force is generated in the torque cylinder, which causes rotation thereof. As the impeller is free, and the casing outflow 32 is towards the top of the structure, the liquid pressure within the casing 30 is such that P1<P2. Accordingly, the impeller will float upwards and the center of the impeller O2 can become higher than the center of the casing O1. In order to keep the difference between P1 and P2 at a minimum, the inner wall 31 is attached to the casing. However, when adjusting flow volume and discharge head, keeping P1 and P2 balanced is difficult. As the impeller rises, the torque cylinder can become caught on the can structure 35. As the impeller tilts, the impeller touches the casing at points Q1 and Q2, and the can and torque cylinder touch at points Q3 through Q6. On the inner surface of the casing, wedge devices 33,34 are attached, however when the impeller is tilted, their repulsive force is sharply decreased. (40-L, 41-L) show the position of the impeller and torque cylinder when they are tilted. Moreover, since the torque cylinder is cylindrical in shape, the magnets 36 must be attached to a cylindrical yoke, placing limits on both the number and size of magnets and the radius of effect (RD) to the impeller. Therefore the impeller output is constrained. Also, since the discharge mouth is directly connected to the inner surface of the can, the discharge pressure is equal to the internal pressure. Since the can has electromagnetic material property and thickness constraints placed on it, and pressure resistance constraints thereon, ultimately there are discharge head constraints.

SUMMARY OF THE INVENTION

A centrifugal pump for use with a liquid forms one aspect of the invention. This pump comprises a hollow casing arrangement, a rotor and a magnet arrangement. The hollow casing arrangement defines an interior, an axis intersecting the interior, an intake port for receiving said liquid in use and communicating same to said interior and a discharge port communicating with the interior. The rotor is positioned in said interior and is rotatable about said axis in spaced relation to said hollow casing arrangement. The rotor includes a drive member; a shaft extending axially from the drive member; and an impeller coupled to said drive member by said shaft for rotation therewith and adapted to cause fluid from said interior to be ejected through said discharge port upon said rotation. The magnet arrangement is disposed outside said interior and is adapted to drive rotation of said drive member about said axis in use through the creation of a rotating magnetic field.

A centrifugal pump for use with a liquid and a motor forms another aspect of the invention. The pump comprises a hollow casing arrangement, a rotor and a magnet arrangement. The hollow casing arrangement defines an interior, an axis intersecting the interior, an intake port for receiving said liquid in use and communicating same to said interior and a discharge port communicating with the interior. The rotor is positioned in said interior and is rotatable about said axis in spaced relation to said hollow casing arrangement. The rotor includes an impeller adapted to cause fluid from said interior to be ejected through said discharge port upon said rotation. The magnet arrangement is disposed outside said interior, is coupled to said motor in use and is adapted to drive rotation of said rotor about said axis in use through the creation of a rotating magnetic field. The rotor and casing arrangement are adapted such that, in use, said liquid supports said rotor for rotation substantially about said axis in spaced relation to said hollow casing arrangement.

According to other aspects of the invention, the impeller may be a closed impeller. As well, the hollow casing arrangement may include: a central casing defining a hole through which the shaft extends; a front casing defining, in combination with the central casing, a portion of the interior in which the impeller is positioned; and a rear casing defining, in combination with the central casing, a portion of the interior in which the drive member is positioned. Additionally, in use, the intake port may be horizontally disposed relative to said impeller and the discharge port may be upwardly disposed relative to said impeller.

According to another aspect of the invention, the rotor and casing arrangement may be shaped such that: a first portion of the space between the rotor and the casing arrangement, in use, measured radially, undulates in magnitude around the impeller for stabilizing the rotor against radial movement; and a second portion of the space between the rotor and the casing arrangement, in use, measured axially, undulates in magnitude around the impeller for stabilizing the rotor against axial movement.

According to other aspects of the invention, measured radially, in the direction of rotation of the rotor, in each undulation in the first portion the space between the rotor and the casing arrangement may gradually decrease and then quickly increase. As well, measured axially, in the direction of rotation of the rotor, in each undulation of the second portion the space between the rotor and the casing arrangement may gradually decrease and then quickly increase.

According to other aspects, the impeller may have projecting from axially opposite sides thereof a pair of circular flanges, arranged coaxial with the axis; the casing may have defined therein a pair of circular channels in which the flanges rotate; the channels may have defined therein a plurality of first wedge-shaped protuberances; and the spaces between the flanges, channels and first wedge-shaped protuberances may define the first portion.

According to another aspect of the invention, the first wedge-shaped protuberances may be circumferentially spaced-apart from one another and disposed radially outwardly from the flanges.

According to another aspect of the invention, the casing arrangement may have defined thereon, on axially opposite sides of and in spaced relation to the impeller, a plurality of second wedge-shaped protuberances; and the spaces between the impeller and the second wedge-shaped protuberances may define the second portion.

According to another aspect, the second wedge-shaped protuberances may be formed on a pair of annular inserts fitted in hollows formed, respectively, on the front and central casing.

According to another aspect of the invention, the rotor and casing arrangement may be shaped such that a third portion of the space between the rotor and the casing arrangement, in use, measured radially, undulates in magnitude around the drive member for stabilizing the rotor against radial movement.

According to another aspect of the invention, measured radially, in the direction of rotation of the rotor, in each undulation of the third portion the space between the rotor and the casing arrangement may gradually decrease and then quickly increase.

According to another aspect of the invention, the drive member may have projecting in an axial direction therefrom a circular flange, arranged coaxial with the axis; the casing arrangement may have defined therein a circular channel in which the flange rotates in use; the channel may have defined therein a plurality of first wedge-shaped protuberances; and the space between the flange, channel and first wedge-shaped protuberances may define the third portion.

According to another aspect of the invention, the first wedge-shaped protuberances may be circumferentially spaced-apart from one another and disposed radially outwardly from the flange projecting from the drive member.

According to another aspect of the invention, said adaptation of the rotor and casing arrangement, such that said liquid supports said rotor in use for rotation substantially about said axis in spaced relation to said hollow casing arrangement, may comprise: a first wedge device which arrests radial translation of the rotor in use; and a second wedge device which arrests axial translation of the rotor in use.

According to another aspect of the invention, the pump may further comprise a first wedge device which arrests radial translation of the rotor in use; and a second wedge device which arrests axial translation of the rotor in use.

According to other aspects of the invention, the shaft may have positioned thereon at least one wing for arresting liquid flow from the impeller towards the drive member in use.

According to another aspect of the invention, at least one wing may be a a spiral wing.

According to another aspect of the invention, the pump may further comprise a conduit providing for fluid communication between a portion of the interior in which the drive member is positioned and the intake port.

According to another aspect, the drive member may comprise: a rotor plate having a rim; and a non-magnetic electrical conductor secured to said rim, the conductor having a surface coated in an insulator. As well, the casing arrangement may include a non-magnetic electrical insulating barrier between the conductor and the magnet arrangement, and the magnet arrangement may comprise two sets of permanent magnets surrounding said conductor and rotatable in use such that, upon said rotation, said rotating magnetic field is generated between the two sets of magnets to intersect the conductor.

According to another aspect of the invention, the conductor may be an annular disc and each of the two sets of permanent magnets may include an even number of permanent magnets arranged in an arc and attached to a yoke, the yokes of the two sets being connected together and the two sets of permanent magnets being axially spaced from one another.

According to another aspect of the invention, the conductor may be a hollow cylinder and each of the two sets of permanent magnets may include an even number of permanent magnets arranged in an arc and attached to a cylindrical yoke, the yokes of the two sets being connected together and the two sets of permanent magnets being radially spaced from one another.

The combination of the motor with a centrifugal pump, with the motor being coupled to the magnet arrangement and, in use, driving said magnet arrangement to create said rotating magnetic field, forms yet another aspect of the invention.

Notably, in these centrifugal pumps, the impeller and connected parts rotate substantially entirely without rubbing against the adjacent structures, and have no seals or immersed bearings. Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter being briefly described hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of a pump constructed according to a first preferred embodiment of the invention with torque device 1 installed;

FIG. 2 is a diagram of a dual layer wall of the front casing

FIG. 3 is a plane figure operational diagram of Wedge Device 2

FIG. 4 is an X1-Y1 cross-sectional diagram of FIG. 3

FIG. 5 is a cross-sectional Diagram of Wedge Device 1

FIG. 6 is an X2-Y2 cross-sectional diagram of FIG. 5

FIG. 7 is a diagram of Wedge Device

FIG. 8 is a diagram showing range of the wedge effect with the use of wedges

FIG. 9 is a diagram showing range of the wedge effect without the use of wedges

FIG. 10 is an external side view diagram of Torque Device I

FIG. 11 is an X3-Y3 direction plane diagram of FIG. 10

FIG. 12 is an X4-Y4 direction plane diagram of FIG. 10

FIG. 13 is a diagram showing the relationship between the rotor plate, torque disc, primary and secondary magnets

FIG. 14 is an X5-Y5 direction plane diagram of FIG. 13

FIG. 15 is a cross-sectional diagram of a pump constructed according to a second preferred embodiment of the present invention, with Torque Device II installed

FIG. 16 is an external side view diagram of Torque Device II

FIG. 17 is an X6-Y6 direction plane diagram of FIG. 16

FIG. 18 is a curve showing the relationship between Torque, Repulsive Force, Wedge Effect, Slip

FIG. 19 is a skeleton diagram of a prior art pump

DESCRIPTION OF THE INVENTION

FIG. 1 and FIG. 15 are cross-section diagrams of pumps constructed according to a first preferred embodiment and a second preferred embodiment, respectively, of the invention. The pumps are generally similar in structure and operation to one another, but for the form of a torque generation device/drive member employed therein. FIGS. 1, 15 show the pumps with Torque Generation Device I (104) and Torque Generation Device II (104′)) installed, respectively, which Devices I, II are fully described hereinafter.

Generally, each pump is comprised of three casings, namely, front casing (1), central casing (2) and rear casing (3), which are connected together to form a hollow casing arrangement having an interior designated with general reference numeral 100. The interior has an axis A-A. Within a portion 110 of the interior 100, the impeller (6) is positioned. The front casing contains an inner wall (1-1) which has a double layer construction. It also contains the inflow mouth or intake port (4) and discharge mouth or port (5). Attached between the sides of the front casing (1) and impeller (6) and the central casing (2), are Wedge Devices 1 (8,9) and Wedge Devices 2 (11,12). The front (1), central (2) and rear (3) casings, with the impeller (6), form the main body of the pump, and regardless of whether Torque Generation Device I or II are installed, the construction of this main body is the same in these preferred embodiments.

In a portion 112 of the interior 100 between the central casing (2) and rear casing (3) is positioned a resin disc (hereafter referred to as the rotor plate) that forms the core (A20 or B20) of each of Torque Generation Devices I, II. Passing through the center of the central casing (2) is a throughhole 108 through which passes a connective shaft (7) that connects the impeller (6) to the rotor plate (A20 or B20). The impeller (6), shaft (7) and Torque Generation Device I or II together define a rotor (1102). This connective shaft (7) has neither bearings nor a seal device. Attached to the connective shaft (7) are several small spiral wings (15) which serve to prevent or arrest the flow of liquid along the throughhole 108. Attached to the rotor plate and the corresponding casing face, is a further Wedge Device 1 (10). Also, in order to obtain balanced internal pressure, a tube (16) (hereafter referred to as the pressure equalization tube) connects the interior of the pump proximal to the Torque Generation Device to the inflow mouth (4).

The Torque Generation Device is a device that generates the impeller driving power, the construction of which is described as follows. Attached to the rotor plate (A20,B20) are either torque disc (A-21) or a torque cylinder (B-21), which are isolated by a non-magnetic electrical insulating can (A3-C, A2-C). By rotating a series of permanent magnets on the outside of the can, a rotating magnetic field is generated which intersects the torque disc (A-21) or torque cylinder (B-21). The torque disc (A-21) or torque cylinder (B-21) is made from a non-magnetic electrical conductor, the surface of which is insulated. The group of magnets form part of a magnet arrangement 106 and are synchronously rotated by a motor (29) to create a rotating magnetic field. Also, the rotating parts of the magnets are covered by a cover.

The effects achievable by this invention will be described below. The inner wall (1-1) is attached inside the impeller casing, and the impeller (6) is arranged within the inner wall (1-1). Placed symmetrically within inner wall (1-1) are discharge holes (1-1-1, 1-1-2). The upward discharge holes (1-1-1) are shifted slightly from being directly under the casing discharge mouth (5). While this prevents the vertical direction liquid pressure from being completely equal, it does lessen the overall difference. Furthermore, the wobble of the impeller (6) is minimized, allowing it to rotate roughly in the center of the can (A3-C, A2-C, B3-C), preventing rubbing against the inner wall (1-1). Attached to both sides of the impeller (6) plate, and one side of the rotor plate (A20) are some cylindrical protrusions or flanges (6-1). Defined into the corresponding inside of the casing are annular channels (1-3) into which these protrusions are fitted. A plurality of first wedge-shaped protrusions (8-1) are defined on or secured to the surface of the channels, radially outwardly from the flange. Each flange (6-1), along with the channel in which it is positioned, and the first wedge-shaped protuberances (8-1) projecting into said channel, define a respective Wedge Device 1 (8,9,10). With these Wedge Devices 1, a repulsive force is generated whenever the impeller (6) or rotor plate (A20,B20) approach the top or bottom faces of the surrounding wall, and this prevents both the impeller (6) and rotor plate (A20) from rubbing against the surrounding wall in the vertical direction. That is, Wedge Devices 1 serve to minimize radial movement or translation of the rotor (i.e. movement that is not parallel to the axis A-A). A Wedge Device 2 is provided for each face of the impeller (6). Wedge Device 2 takes the form of an annular insert plate (11,12) fitted in a matching hollow defined in the casing surfaces facing the impeller faces. These Wedge Devices 2 are provided with a plurality of second wedge-shaped protrusions (8-2). These Wedge Devices 2 generate a repulsive force whenever the impeller (6) approaches the casing in the horizontal or axial direction, i.e. parallel to axis A-A, preventing the impeller (6) from rubbing against the casing from the left and right.

The details of each part of an actual realization of the pump, are explained in the figures described below. Those parts in the drawings that are labeled with an A (e.g. A20) are related parts to Torque Generation Device I, whereas those that are labeled with a B (e.g. B20) are related to Torque Generation Device II. FIG. 2 shows the front casing (1), its inner wall (1-1) and the casing internal pressure. The impeller (6) is within the inner wall, and the liquid passage (1-2) is between the casing (1) and the inner wall (1-1). The liquid passage is connected to the discharge mouth (5). Within the inner wall (1-1) are symmetrically placed discharge holes (1-1-1, 1-1-2), placed such that they are not directly underneath the discharge mouth (5). This makes the difference between P1 and P2 smaller, and protects against unnecessary core wobble of the impeller. With respect to the position of the discharge mouth (5), the liquid pressure within the inner wall and the impeller are such that P1<P2, and making P1=P2 is exceedingly difficult. When P1<P2, the center of the impeller (O 2) will wobble from the casing center (O 1) towards the lower pressure P1 side, making it possible for the impeller (6) to rub up against the inner wall (1-1). When the impeller (6) is stopped, it falls, touching the inner wall on its bottom side, but when it starts to rotate, it simultaneously lifts up from the inner wall. While in operation, in order to for the impeller (6) not to touch the surrounding walls, it is necessary for the impeller to rotate in the center of the casing as much as possible without wobbling. In order to minimize the wobble, Wedge Devices 1 and Wedge Devices 2, are provided. In other words, it is desirable that O 1 and O 2 are roughly aligned during operation.

FIG. 3 is a plane figure diagram of Wedge Device 2 (11), of which FIG. 4 is a X1-Y1 cross-section. This wedge device comprises an insert (11) attached to the inner wall of the casing, and interacts with rotating parts (e.g. the side of the impeller) such that it prevents contact of the impeller with the casing. If there is no liquid or liquid flow between the wedge surface (11-1) and the side of the impeller (6) there will be no wedge effect, therefore an appropriate space, in the form of a liquid entry guide (11-2) has been left out. In the event that the impeller (6) is tilted (6-L), the wedge effect will decrease dramatically. The second wedge-shaped protrusions (8-2) on the insert (11) are such that, measured axially, a second portion (116) of the space (118) between the rotor and the casing arrangement undulates in magnitude around the impeller; more specifically, in the direction of rotation of the rotor, it repeatedly gradually decreases and then quickly increases.

FIG. 5 is a cross-sectional diagram of the Wedge Device 1 (8) that is in between the impeller (6) and the front casing (1). FIG. 6 is an X2-Y2 cross-sectional diagram of FIG. 5. Within the cylindrical opening or channel (1-3) in the front casing (1), a cylindrical protuberance or flange (6-1) on the impeller (6) is inserted. About the outer circumference of the inner face of the hole or channel (1-3), several first wedge-shaped protuberances (8-1) are attached or formed. The first wedge-shaped protrusions (8-1) are such that, measured radially, a first portion 114 of the space between the rotor and the casing arrangement undulates in magnitude around the impeller, more specifically, in the direction of rotation of the rotor, it repeatedly gradually decreases and then quickly increases. The flange (6-1), channel (1-3) and protuberances (8-1) together define Wedge Device 1 (8), which serves to prevent the rotating parts (6-1) from contacting with the top and bottom faces of the casing. When the rotating parts are stopped, they touch the bottom face, but when starting to rotate, they simultaneously separate.

FIG. 7 is an explanatory diagram of the basic operation of the wedge effect provided by Wedge Devices 1,2. In between the stationary side (Z1) and the rotary side (Z2) there is a narrow gap (h₁). Liquid in h₁ rotates due to the rotation of the rotary side. The wedge pieces (WG) are attached to the stationary side, with length α, width β, inclination θ, liquid viscosity μ. The number of wedge pieces is designated as n.

While the rotary side (Z2) rotates, it variously approaches and separates from the stationary side. In other words, the space between the rotary side and stationary side undulates in magnitude, in each undulation, gradually decreasing and then quickly increasing. If one designates the largest separation gap between the rotary side and the wedges as (h₂) and the smallest separation gap as (h₀). then the force of the wedge effect (F), or in other words, the force that resists the further approach of the rotary side, is explained briefly below:Effect Force: F)=K·μ·ν·α·β²·n·1/h₀² where K is the proportionality constant, μ the liquid viscosity, ν is the speed of rotation, α is the length of the wedge face, β is the width of the wedge face, h₀ is the smallest gap size, and n the number of wedge faces.

Accordingly, as Z2 approaches, h₀ becomes smaller, and the repulsive force becomes geometrically larger. The angle of inclination θ affects both the point of maximum wedge effect power on the wedge face as well as the overall repelling power. Regarding the illustrated device, θ=2-4°, h₀=0.1-0.3 mm has been set as a standard. Also, it has been empirically verified that when the surfaces Z1 and Z2 are not parallel, and rather inclined to one another, the wedge effect decreases dramatically. Also, if the corresponding face on Wedge Device 2 is a plane surface, and inclined wedges are not attached, there will be no wedge effect. As the rotary side (Z2) is free, when it stops, it touches the stationary side (Z2) to the bottom of it. At that time, h₀=0. When the pump is switched on, the pressure buildup due to the flow of liquid reaches it's maximum, pushing up Z2 and h₀<>0. In other words, Z2 separates from Z1. That this phenomenon occurs simultaneously when the pump is switched on confirms that Z1 and Z2 do not rub against one another.

FIGS. 8 and 9 show that if both the stationary and rotary sides are cylindrical, even if there are no wedges placed on both sides of the gap, then to some degree the wedge effect will appear when the gap changes, but if the wedges are attached, the effect is larger. FIG. 8 considers the situation with wedges, and FIG. 9 considers the situation without wedges. The bounding limit for the wedge effect is such that α1>>α2.

FIG. 1 and FIG. 15 show the connective shaft (7), which passes through the hole (108) in the center of the central casing (2), connecting the rotor plate (A20, B20) to the impeller (6). Attached to this shaft are a number of small spiral wings (15). During operation, some of the liquid that heads towards the discharge mouth (5) because of the rotation of the impeller (6), passes through this hole and enters the gap (G) between the rotor plate and central casing (2), and the rear casing (3) and rotor plate (A20 or B20). When this happens, the rotation of shaft wings (15) protects against the liquid influx into this gap, and also protects against rising liquid pressure inside this gap. However, since the liquid pressure in this gap does rise gradually, a tube (16) is attached which connects the gap to the low liquid pressure inflow mouth (4), thus protecting against rising liquid pressure within the gap. Furthermore, when (16-1) goes above a set pressure, it opens and acts as relief valve. By doing this, one can be fairly confident that the gap or can (A2-C, A3-C and B3-C) internal pressure is maintained at a constant level, without any relation to the impeller discharge pressure, in other words, the change in discharge head, thus making it possible to deal with changing the discharge head. In other words, it is possible to also have a high discharge head. The can is made of a non-magnetic electrical insulating material and to be strong enough to withstand moderate pressures. There are times when residual air builds up within the gap. When this residual air becomes too much, there is a possibility that it might flow into the impeller and cause harm, so a valve (16-2) is provided to discharge it at that time. Traditional construction, which connects the impeller directly to the torque generating part, fails to produce the above effects, and is only achievable by the disconnected construction used in this invention.

Next, Torque Generation Device I will be described as shown in FIGS. 1, 10, 11, 12, 13, and 14. In front of the code for each part which is related to Torque Generation Device I is the letter A. For example, A20, A21 etc. The right side of FIG. 1 is a longitudinal cross section of the whole device. As seen in FIG. 1, a Wedge Device 1 (10) is provided on the rotor plate (A20) and the corresponding face of the central casing (2). The space between the first wedge-shaped protrusions and flange of Wedge Device 1 (10) define a third portion (120) of the space between the rotor and casing arrangement which, measured radially, undulates in magnitude about the drive member. Attached to the rim of the rotor plate (A20) is the annulus of the Torque Generating Disc (hereafter referred to as the Torque Disc (A-21)). Torque Disc (A-21) is an annulated disc made of a non-magnetic electrical conductor of appropriate thickness and width, the surface of which is covered in an insulating resin (A21-1). FIG. 10 is an external side view drawing of Torque Generation Device I.

FIG. 11 is an overhead X3-Y3 plane view of FIG. 10, and a plane diagram of the primary magnets (A22) as installed into the yoke plate (A24). The magnets (A22) are placed in an arc, in an even number, such that the surface of the adjacent magnet will have opposite polarity, and they will alternate in polarity throughout. The yoke plate (A24) is made out of a magnetic material (e.g. a metal plate) of appropriate thickness, such that a sufficient amount of magnetic flux from each magnet will pass through the plate completely. The primary yoke plate (A24) is connected to the secondary magnet's yoke plate (A25) at the cylindrical part (A25-2) by bolts (A26) at several places. The separation distance between each magnet is designated as g₁. As for the magnetic material used in this device, Neodymium magnets (NF-40/45) are used as the standard. The size of the magnetic gap (g₀), and the thickness of the magnet (WD) are chosen to satisfy the following condition: that the magnetic flux between primary and secondary effectively intersect through the Torque Disc (A21). In other words, they are arranged to minimize leakage flux, and g₀<g₁, g₀<WD.

FIG. 12 is an overhead X4-Y4 plane drawing of FIG. 10, and a plane drawing of the secondary magnets (A23) as installed in the yoke plate (A25). The yoke plate (A25) is of a magnetic material, and the part into which the magnets are attached is a disc (A25-1). The part which connects it to the primary magnet's yoke plate (A24) is in the form of a cylinder (A25-2). For the ease of assembly and disassembly, this yoke (A25) can be split from top to bottom into two pieces; (A25-3) shows the split. The material and arrangement shape of the secondary magnets are completely identical, and the installation arrangement is symmetrical to that of the primary magnets. That is to say, the polarity of the primary magnet is the opposite to that of the corresponding secondary magnet.

FIG. 13 shows the arrangement relationship of the primary magnets (A22) the secondary magnets (A23) and the torque generation disc (A21). FIG. 14 is a X5-Y5 overhead view of FIG. 13, showing the torque plate (A21) which is attached to the rotor plate (A20) and its insulating plate (A21-1). The torque disc (A21) is an annulated disc of appropriate thickness to generate an effective amount of torque, and is made of a non-magnetic electrical conductor (Cu, Al etc.). This is attached to the rim of the rotor plate, and one of its sides is covered in a resin plate (A21-1). These parts are all glued together. The rotor plate coating does not use thermal spray resin coating since insulating plates made of a thermal spray coating have a limit on their processing thickness, and also are porous, such that there is a danger of liquid permeating as far as the torque disc. The primary and secondary magnets sandwich the can (A2-C, A3-C), which in turn sandwiches the torque disc, allowing for synchronous rotation. If at the torque disc thickness is designated t0, the thickness of both sides of the insulating material designated as t1, the can (A2-C,A3-C) thickness t2, the distance between the primary and secondary magnets as g₀, the gap between the can (A2-C, A3-C) and the torque disc as g₂, and the gap between the can and the primary and secondary magnets each as g₃, then the distance between the primary and secondary magnets, or the magnetic gap becomes: g₀=t0+2t1+2t2+2g₂+2g₃. Within this invention if to is 3-4 mm, t1 is 1.5-2 mm, t2 is 3-4 mm, g₃ is 0.5-1 mm, g₂ is 0.5-1 mm, then g₀ is approximately 20 mm. FIG. 14 is a an X5-Y5 plane diagram of FIG. 13 that shows the relationship between the rotor plate (A20) the attached torque disc (A21) the torque disc insulator (A21-1) and the torque effective radius of operation of the torque disc.

Next, Torque Generation Device II will be described as shown in FIGS. 15, 16, and 17. In front of the code for each part which is related to Torque Generation Device II is the letter B. For example, B20, B21 etc. FIG. 15 is a cross-sectional drawing of the whole device. The main body of the pump is the same as in FIG. 1. and a separate drawing is therefore omitted. The right side of FIG. 15 is a longitudinal cross section of the Torque Generation Device II. Wedge Device 1 (10) is attached to the rotor plate (A20) and the corresponding face of the central casing (2). Attached perpendicularly to the rim of the rotor plate is the Torque Cylinder (B21). The Torque Cylinder is a cylinder of appropriate length and thickness, made of a non-magnetic electrical conductor, the surface of which is covered in an insulating resin.

FIG. 16 is an external view of Torque Generation Device II, and FIG. 17 is an X6-Y6 cross-sectional diagram of FIG. 16. The torque cylinder (B-21) is separated from the 2 layer cylinder can (B3-C) by a gap (g₂). The can is connected at both ends with the central casing (2) and the rear casing (3). The can is made of a non-magnetic electrical insulator.

The torque cylinder is sandwiched by the can, which in turn is sandwiched by two set of magnets. On the outside, the primary magnets (B22) are installed, on the inside, the secondary magnets (B23) are installed. The outside and inside magnets are each attached to their respective cylindrical magnetic yokes (B25-1, B25-2). The size of both the inside and outside magnets are roughly the same, and are provided in the same even number. The corresponding inside and outside magnets have opposite polarities to one another. As well, each adjacent magnet also has the opposite polarity. If the distance between the inside and outside magnets, (i.e. the magnetic gap), is designated g₀, the distance between each adjacent magnet (g₁), the effective width of the magnets (WB), the thickness (WD), then the conditions g₀<g₁, g₀<WD are the same as with Torque Device I. The inside and outside magnets are attached to the yoke cylinder (B25-2) outer surface and B25-1's inner surface respectively. (B25-1) and (B25-2) are attached together by bolts (B26) to the yoke disc (B24), and are synchronously rotated by a driving motor (29). In this device as well g₀ is roughly 20 mm, and the standard magnets used are NF-40. When compared to ordinary general purpose pumps, the value for g₀ is quite large, around 20 mm in Torque Device I and II. When g₀ is large, and trying to generate a rotating magnetic field in g₀ with a wrapped coil device, excitation losses are especially large, and there is heat generated. Also, it becomes difficult to use this pump for explosion prevention applications. For the reasons above, this invention uses a design of generating a magnetic field by rotating a series of permanent magnets, and by this design it is expected that there will be a benefit of preventing the above inefficiencies.

The torque (T₀) generated by one pair of magnets in the torque disc or torque cylinder is as follows: $\begin{array}{c}{T}_o=K_1·\theta ·I\alpha ·R\\ =K_1·\theta ·e/\mathrm{\rho \gamma }·R\\ =K_1·\theta ·K_2\theta n_{o}S/\mathrm{\rho \gamma }·R\end{array}$ The torque imparted on the impeller is:T=K·θ²·n_o·S·1/ρÖγ·R·NP

The primary and secondary magnets, and the inner and outside magnets are treated as the primary and secondary magnets, and the torque disc and torque cylinder are treated as the torque disc.

K, K1, K2 proportionality constant
Θ         magnetic flux density between primary and
          secondary magnets that induces e
e         the voltage induced in the torque disc or inside the
          torque cylinder by change in phi
ργ        electric resistance of the torque disc or torque
          cylinder (dependent on thickness and material)
no        rpm of the magnets (identical to motor rpm)
n         rpm of the torque disc
S         (S = no − n/no) the slippage with respect to no
          by the torque disc or torque cylinder
R         radius of effect (RA or RB)
NP        the number of pairs of the primary and secondary
          magnet
I         eddy current according to the Fleming Rule

Also, phi's magnitude is inversely proportional to g₀, proportional to WB, and nearly unrelated to WL. According the above equation, in order increase the torque T, and the pump's discharge power, it is necessary to make the number of pairs of attached magnets and the radius of effect (RA or RB) structurally large. In this respect, comparing this invention to earlier devices (see FIG. 19) RA or RB are larger than RD, and there are a greater number of pairs of attached magnets, this invention is able to have a greater capacity.

FIG. 18 is a diagram that shows the properties of, the repulsive force due to Wedge Device I (FA), the electromagnetic repulsion (Fm), Torque (T), and the slip (S) while the pump is operating, between the rpm of the torque disc or torque cylinder and the rpm of the magnets. The torque T is the same for Torque Generation Device I and II, but the Electromagnetic repulsion (Fm) has a different direction from Torque Device I to II, and the repulsive force from Wedge Device 1 (FA) is the same for both Torque Generation Devices. The Electromagnetic repulsion (Fm) is a cross product of the magnetic Reynolds number (Rm) and the slip, and appears between the magnets and the torque disc or torque cylinder when S*Rm>1. In other words, with Torque Device I it appears laterally between the torque disc and the magnets, and with Torque Device II, it appears vertically between the torque cylinder and the magnets. Here, the magnetic Reynolds number (Rm) is a value that comes from the electromagnetic configuration, speed of the rotating parts, and the slip, the electromagnetic repulsion is at its maximum during activation. When stopped, Wedge Device I has h₀=0, and the rotating parts, are touching the bottom of the casing, but when starting the repulsive force due to the flow of liquid is at its greatest, such that the rotating parts separate from the casing. The combined force of Fm and FA is shown in the Fm+FA curve. Also, if a brake is added to the driving motor, when decelerating to an appropriate speed, the brake is engaged, then stopping will be gradual and smooth, and no rubbing will occur.

The disassembly and assembly of the pump when Torque Device I is installed is described hereinafter with reference to FIG. 1. As a first step, by releasing connecting bolts (13,14) and the impeller restraining screw (7-1), the front casing (1) and the impeller (6) can be removed. Release of bolt (27-1), and removal the cover (27), can be followed by removing bolt (A26) and the secondary magnet yoke split bolts (A25-4). The secondary magnets and the yoke part can then be removed. Finally, by removing the can restraining screws (A3-C-1), the central casing (2), connective shaft (7), rotor plate (A20) and rear casing (3) can be removed. In assembly, the above steps can be followed in reverse.

With regard to the matter of the disassembly and assembly of the pump when Torque Device II is installed, a first step is the removal of connecting bolts (13,14) and the impeller restraining screw (7-1). Thereafter, all the parts can be disassembled. For the purpose of assembly, the above steps can be followed in reverse. In comparison to the first preferred embodiment of the pump, assembly and disassembly of the second preferred embodiment of the pump is extremely simple, and when there exists a need for frequent cleaning and internal inspection, the second preferred embodiment is an advantageous selection.

The centrifugal pumps described herein can handle pure water, as well as corrosive liquids (including acids, alkalis and electrolytic corrosive liquid) without a problem, other uses include suction or removal of all variety of liquids, such as fine slurry mixtures, etc. It can be used in a wide range of technical fields.

Specification of the test machine, and the test results are according to Table 1 below. Unless otherwise specified, parts in the table are all made from ultra high density polyethylene. Units of measurement are in mm.

TABLE 1
		Torque Gen	Torque
Item	Detail	Device I	GenDevice II
Front casing	Inflow Diameter * Outflow Diameter	65A * 40A	50A * 25A
	Internal Double Layer Wall	Yes	Yes
Impeller	Outer Diameter * Inner Diameter	Θ150 * θ60	Θ140 * θ50
	No. Wings	6	5
	Rotation Per Minute	3300	r.p.m.	3200	r.p.m.
	Specific Speed	177	ns	137	ns
Wedge Device 1	Number attached	3	3
Wedge Device 2	Number attached	2	2
Connective Shaft Wings	Quantity	8	8
Rotor Plate	Outside Diameter	Θ200	Θ180
Torque Disc/Torque Cylinder	Material	99%	Cu	99%	Cu
	Outer Diameter/Inner	Θ190/110/4	Θ175/167/(4)
	Diameter/Thickness (Width)
	Radius of effect (R)	93	85
Can	Thickness	3	3
Attached Magnets	Material (Neodymium Magnets)	NF-40	NF-40
(attachment yoke material, SS-	No. Attached	10	8
400, thickness 10 mm)	Magnetic Gap (go)	≈20	≈20
Driving Motor (AC 220/200 V *	Rated RPM 3420 r.p.m. * with Break	7.5	kW	5.5	kW
2 P * 60 Hz)
Test Results (no empty runs)	Discharge Head (m)	40	30
	Flow Rate (L/min)	≈500	≈400
	Torque Disc/Torque Cylinder slippage	≈3.5%	≈6%
	(%)
	Efficiency (%)	43	35
	Rubbing Parts	None	None

PARTS LIST
1	Front Casing	1-1	Casing Inner Wall
1-1-1	Casing Inner Wall Discharge Hole	1-1-2	Casing Inner Wall Discharge Hole
1-2	Liquid Flow Path	1-3	Cylindrical groove
2	Central casing	2-1	Support Plate
A2-C	Can (Partition) Portion	3	Rear Casing
A3-C	Can (Partition) Portion	A3-C-1	Can Restraining Screw
B3-C	Can	4	Inflow or intake port
5	Outflow (discharge mouth or port)	6	Impeller
6-1	Cylindrical protrusions or flanges	6-L	Inclined impeller position
7	Connective shaft	7-1	Connecting Screw
7-2	Connecting Screw	8	Wedge Device 1
8-1	First wedge-shaped protrusion	8-2	Second wedge-shaped protrusion
8-g	Wedge Gap	9	Wedge Device 1
10	Wedge Device 1	11	Wedge Device 2
11-1	Wedge Surface	11-2	Liquid entry guide
11-G	Minimum Gap	12	Wedge Device 2
13	Connective Bolt	14	Connective Bolt
15	Screw wings	16	Pressure equalization tube or
			conduit
16-1	Relief valve	16-2	Open-close valve
A20	Rotor plate	A21	Torque disc
A21-1	Cover plate	A22	Primary Magnets
A23	Secondary Magnets	A24	Primary Magnet Yoke
A25	Secondary Magnet Yoke	A25-1	Secondary Magnet Yoke Plate
A25-2	Secondary magnet yoke cylinder	A25-3	Secondary Magnet Yoke split
A25-4	Yoke split connective bolt	A26	A24-A25 connective bolts
B3-C	Can	B20	Rotor Plate
B21	Torque cylinder	B22	Outer (Primary) Magnets
B23	Inner (Secondary) Magnets	B24	Connective yoke plate
B25-1	Outer Magnet Yoke Cylinder	B25-2	Inner Magnet Yoke (Inner Yoke
	(Outer Yoke Cylinder)		Cylinder)
B26	B25-1, B25-2, B26, Connective	G	Gap between rotor plate, and
	Bolt		central and rear casings
27	Protective cover	28	Thrust bearing
29	Driving motor	30	Impeller casing
31	Inner wall	32	Outflow (discharge mouth)
33	Wedge Device 2	34	Wedge Device 2
36	Inner, Outer Magnets	37	Driving Motor
40	Impeller	40-1	Inclined impeller position
41	Torque cylinder	41-L	Inclined Rotor position
O1	Center of the casing	O2	Center of the impeller
P1	Pressure between the impeller and	P2	Pressure between the impeller and
	inner wall at the top		the inner wall at the bottom
LQ	Liquid in the wedge gap	V	Velocity of the moving side
			(rotational velocity)
α	Wedge Length	β	Wedge Width
Θ	Wedge Inclination	WG	Wedge
h1	Maximum Wedge Gap	h0	Minimum Wedge Gap
Z1	Stationary Side	Z2	Rotary size
A1	Effective Range of the Wedge	α2	Effective Range of the Wedge
	Effect		Effect
WB	Vertical Width of the Magnet (the	WL	Horizontal width of the magnet
	width that crosses the direction of		(the width that is concurrent with
	rotation of the torque disc or		the direction of rotation of the
	torque cylinder)		torque disc or torque cylinder)
WD	Thickness of the Magnet	go	Distance between the primary and
			secondary magnets (magnetic gap)
g1	Distance between the magnets	g2	The gap between the can and the
			torque disc (A21) or torque
			cylinder (B21)
g3	The distance between the can and	RA	Radius of effect
	the magnets
RB	Radius of Effect	RD	Radius of effect
S	slip	T	Torque
F	Electromagnetic attractive force	Fm	Electromagnetic repulsive force
FA	Repulsive force due to the wedge	S1	Slip during normal operation
	effect
Q1	Contact points between impeller	Q2	Contact points between impeller
	and casing		and casing
Q3-Q6	Contact points between the rotor	100	Interior of casing assembly
	and the can
A—A	Axis of casing assembly	102	Rotor
104, 104′	Drive member	106	Magnet arrangement
108	Hole through central casing	110	Portion of interior surrounding
			impeller
112	Portion of interior surrounding	114	First portion of interior space
	drive member
116	Second portion of interior space	118	Space between rotor and casing,
			generally
120	Third portion of interior space	35	Can structure

Finally, it is to be understood that while but two embodiments of the present invention have been herein shown and described, it will be understood that various changes in size and shape of parts may be made. It will be evident that these modifications, and others which may be obvious to persons of ordinary skill in the art, maybe made without departing from the spirit or scope of the invention, which is accordingly limited only by the claims appended hereto, purposively construed.

Claims

1. A centrifugal pump for use with a liquid, said pump comprising: a hollow casing arrangement defining an interior, an axis intersecting the interior, an intake port for receiving said liquid in use and communicating same to said interior and a discharge port communicating with the interior; a rotor positioned in said interior and rotatable about said axis in spaced relation to said hollow casing arrangement, said rotor including: a drive member; a shaft extending axially from the drive member; and an impeller coupled to said drive member by said shaft for rotation therewith and adapted to cause fluid from said interior to be ejected through said discharge port upon said rotation, and a magnet arrangement disposed outside said interior and adapted to drive rotation of said drive member about said axis in use through the creation of a rotating magnetic field.

2. A centrifugal pump for use with a liquid and a motor, said pump comprising: a hollow casing arrangement defining an interior, an axis intersecting the interior, an intake port for receiving said liquid in use and communicating same to said interior and a discharge port communicating with the interior; a rotor positioned in said interior and rotatable about said axis in spaced relation to said hollow casing arrangement, said rotor including an impeller adapted to cause fluid from said interior to be ejected through said discharge port upon said rotation; and a magnet arrangement disposed outside said interior, coupled to said motor in use and adapted to drive rotation of said rotor about said axis in use through the creation of a rotating magnetic field, the rotor and casing arrangement being adapted such that, in use, said liquid supports said rotor for rotation substantially about said axis in spaced relation to said hollow casing arrangement.

3. A centrifugal pump according to claim 1, wherein the impeller is a closed impeller; the hollow casing arrangement includes a central casing defining a hole through which the shaft extends a front casing defining, in combination with the central casing, a portion of the interior in which the impeller is positioned; and a rear casing defining, in combination with the central casing, a portion of the interior in which the drive member is positioned; and in use, the intake port is horizontally disposed relative to said impeller and the discharge port is upwardly disposed relative to said impeller.

4. A centrifugal pump according to claim 2, wherein the rotor and casing arrangement are shaped such that a first portion of the space between the rotor and the casing arrangement, in use, measured radially, undulates in magnitude around the impeller for stabilizing the rotor against radial movement; and a second portion of the space between the rotor and the casing arrangement, in use, measured axially, undulates in magnitude around the impeller for stabilizing the rotor against axial movement.

5. A centrifugal pump according to claim 4, wherein measured radially, in the direction of rotation of the rotor, in each undulation in the first portion the space between the rotor and the casing arrangement gradually decreases and then quickly increases.

6. A centrifugal pump according to claim 5, wherein measured axially, in the direction of rotation of the rotor, in each undulation in the second portion the space between the rotor and the casing arrangement gradually decreases and then quickly increases.

7. A centrifugal pump according to claim 6, wherein the impeller has projecting from axially opposite sides thereof a pair of circular flanges, arranged coaxial with the axis; the casing arrangement has defined therein a pair of circular channels in which the flanges rotate in use; the channels have defined therein a plurality of first wedge-shaped protuberances; and the spaces between the flanges, channels and first wedge-shaped protuberances define the first portion.

8. A centrifugal pump according to claim 7, wherein the first wedge-shaped protuberances are circumferentially spaced-apart from one another and disposed radially outwardly from the flanges.

9. A centrifugal pump according to claim 7, wherein the casing arrangement has defined thereon, on axially opposite sides of and in spaced relation to the impeller, a plurality of second wedge-shaped protuberances; and the spaces between the impeller and the second wedge-shaped protuberances define the second portion.

10. A centrifugal pump according to claim 9, wherein the second wedge-shaped protuberances are formed on a pair of annular inserts fitted in hollows formed, respectively, on the front and central casing.

11. A centrifugal pump according to claim 2, wherein the rotor further comprises a drive member and a shaft coupling the rotor to the drive member for rotation therewith, and wherein the magnet arrangement is adapted to drive said rotation of said rotor by causing rotation of said drive member.

12. A centrifugal pump according to claim 11, wherein the rotor and casing arrangement are shaped such that a third portion of the space between the rotor and the casing arrangement, in use, measured radially, undulates in magnitude around the drive member for stabilizing the rotor against radial movement.

13. A centrifugal pump according to claim 12, wherein measured radially, in the direction of rotation of the rotor, in each undulation in the third portion the space between the rotor and the casing arrangement gradually decreases and then quickly increases.

14. A centrifugal pump according to claim 13, wherein the drive member has projecting in an axial direction therefrom a circular flange, arranged coaxial with the axis; the casing arrangement has defined therein a circular channel in which the flange rotates in use; the channel has defined therein a plurality of first wedge-shaped protuberances; and the space between the flange, channel and first wedge-shaped protuberances define the third portion.

15. A centrifugal pump according to claim 14, wherein the first wedge-shaped protuberances are circumferentially spaced-apart from one another and disposed radially outwardly from the flanges.

16. A centrifugal pump according to claim 2, wherein said adaptation of the rotor and casing arrangement, such that said liquid supports said rotor in use for rotation substantially about said axis in spaced relation to said hollow casing arrangement, comprises: a first wedge device which arrests radial translation of the rotor in use; and a second wedge device which arrests axial translation of the rotor in use.

17. A centrifugal pump according to claim 1, further comprising: a first wedge device which arrests radial translation of the rotor in use; and a second wedge device which arrests axial translation of the rotor in use.

18. A centrifugal pump according to claim 3, further comprising: a first wedge device which arrests radial translation of the rotor in use; and a second wedge device which arrests axial translation of the rotor in use.

19. A centrifugal pump according to claim 1, wherein the shaft has positioned thereon at least one wing for arresting liquid flow from the impeller towards the drive member in use.

20. A centrifugal pump according to claim 19, wherein said at least one wing is a spiral wing.

21. A centrifugal pump according to claim 19, further comprising a conduit providing for fluid communication between a portion of the interior in which the drive member is positioned and the intake port.

22. A centrifugal pump according to claim 1, wherein the drive member comprises: a rotor plate having a rim; and a non-magnetic electrical conductor secured to said rim, the conductor having a surface coated in an insulator, the casing arrangement includes a non-magnetic electrical insulating barrier between the conductor and the magnet arrangement, and the magnet arrangement comprises two sets of permanent magnets surrounding said conductor and rotatable in use such that, upon said rotation, said rotating magnetic field is generated between the two sets of magnets to intersect the conductor.

23. A centrifugal pump according to claim 22, wherein the conductor is an annular disc; and each of the two sets of permanent magnets includes an even number of permanent magnets arranged in an arc and attached to a yoke, the yokes of the two sets being connected together and the two sets of permanent magnets being axially spaced from one another.

24. A centrifugal pump according to claim 22, wherein the conductor is a hollow cylinder; and each of the two sets of permanent magnets includes an even number of permanent magnets arranged in an arc and attached to a cylindrical yoke, the yokes of the two sets being connected together and the two sets of permanent magnets being radially spaced from one another.

25. In combination, a centrifugal pump according to claim 2; and a motor, said motor being coupled to said magnet arrangement and, in use, driving said magnet arrangement to create said rotating magnetic field.