GB2567582A

GB2567582A - Electric disc rotor with a pressure reducer for the motor gap

Info

Publication number: GB2567582A
Application number: GB1901686.4A
Authority: GB
Inventors: Sedlak Holger
Original assignee: Efficient Energy GmbH
Current assignee: Efficient Energy GmbH
Priority date: 2016-08-08
Filing date: 2017-08-04
Publication date: 2019-04-17
Anticipated expiration: 2037-08-04
Also published as: GB201901686D0; GB2567582B; DE102016214700A1; WO2018029116A1

Abstract

The invention relates to an electric disc motor comprising a rotor (10) which has an element (105) to be moved; and a stator (20) which is arranged relative to the rotor (10) such that a motor gap (30) is formed between the rotor (10) and the stator (20), wherein the electric disc motor is designed to convey a medium from a source region (90) to a target region (100) by means of the element (105) to be moved, and a target pressure in the target region (100) is higher than a source pressure in the source region (90). The electric disc motor additionally has a pressure reducer (140) for reducing a pressure acting on the rotor on the basis of the different pressures in the source region and in the target region. The pressure reducer is designed such that a pressure in the motor gap (30) is lower than the target pressure and greater than or equal to the source pressure.

Description

Electric Disk Armature Comprising a Pressure Reducer for the Motor Gap

Description

The present invention relates to electric meters, and in particular to electric disk motors.

EP 2 549 113 A2 discloses a magnetic rotor and a rotary pump comprising a magnetic rotor. The rotor may be driven and mounted, by means of a bearing, in a magnetically 10 contactless manner for conveying a fluid within a pump housing inside a stator of the rotary pump. In addition, the rotor is encapsulated by means of external encapsulation oomprising fluorinated hydrocarbon. Within the encapsulation, the rotor includes a permanent magnet jacketed with a metal jacket. The rotary pump includes a pump housing having an inlet for feeding in a fluid and an outlet fur discharging the- fluid. For example, the fluid is a 15 chemically aggressive acid having a proportion of a gas, e.g. sulfuric acid with ozone. For conveying the fluid, a magnetic rotor is mounted, by means of a magnetic bearing, in a contactless manner within the pump housing. Moreover, the rotor is provided with a magnetic drive comprising electric coils. The stator is configured with laminated iron which is operatively connected to the permanent magnet of the rotor. The drive is configured as a 20 motor 'Without a bearing 'wherein the stator is formed as a bearing stator and a drive stator at the same time. The rotor is configured as a disk armature, the axial height of the rotor being smaller than or equal to half a diameter of the rotor.

The dissertation ETH No. 12870, Dec iagerlose Scheibenrnotor” (the disk motor without a 25 bearing;, N. Barletta, 1998, discloses disk motors mounted by means of magnetic bearings. Magnetic bearings operate completely free from contact, wearing, maintenance and lubricant. To actively stabilize a degree of freedom, two variable electromagnets including electronic control are needed. The disk motor without a bearing is employed, within a nonbearing blood pump, as a non-bearing disk motor comprising an active axial bearing, as a 30 miniature disk motor or as a non-bearing bio reactor. By means of a combination of passive reluctance magnetic bearings and a non-bearing motor it is possible to fully mount, by using a bearing, a disk motor with only two actively stabilized radial degrees of freedom. Requirements in terms of a large air gap, which is necessary in hermetic systems, are met by selecting a non-bearing permanent-magnetically excited synchronous motor. A non35 bearing disk motor suitable to drive an axial pump for cardiac assistance is designed for rotational speeds of 30,000 revolutions per minute, which results in a relatively small design size.

Commercial electric disk motors are also known by the name of “pancake motor'. The motor concept presented in both above references >s characterized in that the stator extends around the rotor. Such motors are also referred to as internal-rotor motors.

With the concept of internal-rotor motors there is the problem that the stator must always be larger than the rotor, i.e. the size and configuration of the rotor is always confined by the stator housing, and/or the rotor dominates the configuration of the stator. Thus, the field of application of such a d-sk motor configured as an Internal-rotor motor is limited.

In addition. With disk motors there is the problem, as a matter of principle, that the rotor -s exposed to pressure differences and/or pressures acting in specific directions, irrespective of whether the rotor -s designed as an internal-rotor motor or external-rotor motor. Said pressures result ·η that there Will be a strain upon a bearing in the direction of the pres15 sure acting upon the rotor, and in that, consequently, wearing is increased, and/or ·η that when deflection of the rotor is permitted, the rotor will be deflected in said direction and, therefore, clearances for said deflection must be provided. In particular when the pump is used for pumping a medium from a pressure zone having a first pressure to a pressure zone having a second pressure, or for generating such a pressure difference at ail, ex20 pensive design measures need to be taken to either achieve a required resistance to wear and tear or to provide a clearance for any deflection that may occur.

Ail this results In that the design expenditure of the disk motor increases and that, therefore, its fault liability increases while the field of application is restricted at the same time.

It is the object of the present invention to provide a flexible disk motor concept

This object is achieved by an electric disk motor as claimed in claim 1, a heat pump as claimed in claim 23, or a method of producing an electric disk motor as claimed in claim 30 25.

In accordance with one aspect, the electric disk motor is configured as an external-rotor motor. This means that the rotor comprises a recess which has the stator arranged therein. Thus, the rotor rotates around the stator. This enables that a design of the rotor may be 35 defined directly by the field of use of the rotor rather than by the fact that, as is the case with an internal-rotor motor, one must always ensure that there will still be enough space around the rotor for a stator housing comprising corresponding magnetic coils. On the other hand, media and/or pressure separation of the disk motor is performed in that an encapsulation material is provided around the stator within the motor gap arranged between the rotor and the stator, so that the ent-re stator is separated, in terms of media and 5 pressure, from the zone wherein the rotor is located. Thus, ail of the coil terminals for the motor coils within the stator may easily be guided out of the motor since the entire area of the stator exhibits ambient pressure and/or lies within the ambient medium rather than within the conveying zone 'which has the rotor arranged therein. Thus, any problems related to excess voltage and similar effects which occur when high voltages ere used within 10 areas of low pressure are avoided since all neighboring stator coils are separated from the low-pressure area by the encapsulation material located within the motor gap. This is particularly important when the rotor operates within a low-pressure zone such as within a pressure range below 100 mbar, which occurs when the rotor is employed as a compressor element in a heat pump operating with water as the working medium. However, even if 15 the rotor operates at a pressure higher than that of the stator, the media and/or pressure separation effected by an encapsulation material within the motor gap is of particular advantage

Therefore, by using an external-rotor motor in combination with media/pressure separa/0 ticn by means of an encapsulation material within the motor gap, an electric disk motor is provided which may be manufactured with low expenditure in terms of design, which has no problems regarding excess-voltage effects that would occur if coils were subjected to relatively high voltage in low-pressure areas, and which is particularly suited, in particular, for high rotational speeds The latter advantage results from the fact that permanent mag25 nets attached to the rotor and defining the magnetic gap on the rotor side are supported “toward the outside” by the rotor material itself. This is particularly Important with high rotational speeds such as more than 50,000 revolutions per minute, for example, since the centrifugal forces which arise there may become problematic, in particular with internalrotor motors, to the effect that the permanent magnets there must be secured with a large 30 amount of expenditure.

On the other hand, the larger rotor diameter, which is due to the fact that the rotor is arranged around the stator, in turn is particularly advantageous, in particular, at rotational speeds of more than 50,000 revolutions per minute since in this manner the rotation of the 35 rotor itself and/or its axis of rotation is additionally stabilized, like with a gyroscope. This effect occurs to a lesser degree, or not st all, with electric disk motors having relatively small rotor diameters such as are used for internal-rotor motors, for example.

In a further aspect, the electric disk motor is employed as an external-rotor motor or as an 5 internal-rotor motor. It comprises a rotor having an element that is to be moved, and a stator which is arranged, in relation to the rotor, such that a motor gap is formed between the rotor and the stator. The electric disk motor is configured to convey, by means of the element to be moved, a medium from a source zone to a target zone, a target pressure in the target zone being higher than a source pressure in the source zone. The pressure 10 acting upon the rotor because of the pressure difference is reduced, in accordance with this aspect, by a pressure reducer in the sense that a pressure present within the motor gap, i.e. where magnetic interaction between the rotor and the stator takes place, is smaller than the target pressure and larger than or equal to the source pressure. In this manner, one achieves that the rotor no longer bears any load, or at least bears less load 15 in a specific direction, because of the pressure difference between the source pressure and the target pressure, which would lead to a resulting pressure and, therefore, to a deflection and/or to an increase in wear and tear of the bearing.

This means that even though the rotor may convey the required pressure difference be20 tween the input and the output, i.e between the source zone and the target zone, no such pressure difference, or a reduced pressure difference, will prevail within the motor gap and, therefore, in the area of interaction between the rotor and the stator. Consequently, axial deflection due to operation of the electric disk motor is reduced or even avoided, in the example of a non·-bearing motor that is merely passively mounted in axial terms, e.g. 25 by means of a magnetic bearing.

However, even in an example of a rotor mounted in a contacting manner by means of a bearing, i.e. a rotor mounted with a bail bearing, the pressure reduction results m avoiding that the pressure is transferred onto the bearing and that the wear and tear of the bearing 30 increases. The pressure reduction in the motor gap thus results in that wear and tear of the motor and/or bearing is reduced, or that in the event of wear-free bearings, i.e. contactless bearings, necessary clearances for rotor deflection due to the resulting pressure exerted upon the rotor in a specific direction in an axial or even radial direction may be reduced since due to the operation of the rotor no such deflections occur, or only very 35 small deflections occur as compared to the situation where no specific mechanical pressure reduction is performed.

The pressure reduction within the motor gap is useful for external-rotor motors and internal-rotor motors alike. Even with an internal-rotor motor It is advantageous for the rotor to undergo, during operation, no situation where deflections ere substantially higher than in 5 the idle state. Thus, even with an internal-rotor motor, clearances may be reduced, i.e.

clearances between the rotor and a guide element which demarcates the fluid flow area, within which the rotor acts, toward the outside.

In preferred embodiments, the pressure reduction is performed by two flow resistors, οροί 0 cifically by a first flow resistor arranged between the target zone and the motor gap, and a second flow resistor arranged between the motor gap and the source zone. In particular, the flow resistor between trie motor gap and the target zone is configured to be higher than the flow resistor between the motor gap and the source zone, so that the- flow resistor between the motor gap and the target zone reduces a short-circuit for the pressure, 15 whereas the flow resistor between the motor gap and the source zone achieves that the lower pressure, which also acts in the target zone, acts within the motor gap. In particular when the motor is configured as an external-rotor motor to the effect that the stator is arranged within a recess of the rotor, it is preferred to attach the flow resistor between the target zone and the motor gap as far outside on the rotor as possible, so that as large an 20 area as possible of the rotor face located opposite the stator is arranged in a zone exhibiting the low source pressure, or the pressure which is lower than the target pressure. On the other hand, it is preferred to attach the second flow resistor between the motor gap and the source zone as centrally as possible, i.e. at the relative center within the rotor, so as to achieve that the conditions along the circumference within the motor gap are as 25 similar as possible.

In preferred embodiments, the pressure reducer includes a labyrinth seal between the target zone and the motor gap, which labyrinth seal provides a defined and relatively large flow resistance, and alternatively or additionally, a bore within the rotor between the motor 30 gap and the source zone which provides a relatively small flow resistance. Even utilization of either only a labyrinth seal or only a bore, i.e., utilization of only one flow resistance between the source zone and the motor gap or between the target zone and the motor gap already leads to a pressure reduction within the motor gap and, therefore, to reduced deflection of the rotor with regard to the stator during operation in the event of a non35 contact magnetic bearing and, in particular, in the event of an axially passive bearing, or leads to a reduction in wear in the event of a contact bearing such as a bail bearing, for example, on account of the reduced load during operation.

The First aspect of the encapsulation material within the motor gap and the second aspect of the pressure reducer may preferably be combined to the effect that an external-rotor disk motor comprises both encapsulation within the motor gap and the pressure reducer. However, the two aspects may just as well be alternatives to each other and may be employed, with regard to the pressure reducer, not only for external-rotor motors but also For internal-rotor motors, in addition, both aspects may also be used, separately or jointly, For 10 contact bearings; however, utilization of rotors mounted by means of magnet bearings is preferred, in particular of axially passive bearings, i.e. axially non-ciosed-ioop controlled bearings and radially actively closed-loop controlled magnetic bearings.

Preferred embodiments of the present invention will be explained in detail below with refin erence to the accompanying drawings, wherein:

rig. 1A shows an external-rotor motor in accordance with a first aspect;

shows an electric disk motor in accordance with a second aspect, which is configured as an external-rotor motor or an internal-rotor motor:

Fig. 1C shows an internal-rotor motor in accordance with the second aspect;

Fig. ID shows a preferred implementation of the second aspect comprising two serially connected flow resistors;

Fig. 2A shows a cross section through an electric disk motor in accordance with the first aspect;

Fig. 2B shows a cross section through an electric disk motor in accordance with the second aspect, in which the first aspect is also implemented;

Fig. 3 shows a cross section through a detailed representation of an implementation of the flow resistor by means of a labyrinth seal;

Fig. 4 shows a schematic representation of a rotor and of the forces acting upon it with regard to the second aspect;

Fig 5 shows a schematic; representation of a magnetic bearing in the example of an internal-rotor motor;

Fig. 6 shows a cross sectional representation of an external-rotor motor having an elevated yoke (back-iron) element; and

shows a schematic cross section through a heat pump comprising the electric disk motor in accordance with the first or second aspect.

Fig. 1/X shows a cross section through a schematically depicted electric disk motor comprising a rotor 10 which has an element to be moved, in addition, there is a stator 20, the 15 stator 20 being arranged, in relation to the rotor 10, such that there -s a motor gap 30 between the rotor and the stator. The rotor 10 further includes a recess 40 which has the stator 20 arranged therein.

Moreover, the rotor 10 is arranged within a first zone 50 comprising a first pressure p_v In 20 addition, the stator is arranged within a second zone 60 comprising a second pressure p₃, which differs from the first pressure pi. In the embodiment shown in Fig. 1A, the first pressure is, by way of example, the pressure prevailing inside the electric disk motor of Fig.

1A. By contrast, the second pressure is the ambient pressure or the atmospheric pressure, for example, when the disk motor is arranged in the atmosphere, or is a pressure 25 differing from the atmospheric pressure when the disk motor is arranged in a zone exhibiting a pressure differing from the atmospheric pressure. In addition, the motor gap 30 has an encapsulation material 70 arranged therein by means of which the first zone 50 is separated from the second zone 60. The separation takes place, for example, in that the encapsulation material fully encloses the stator in the embodiment shown in Fig. 1A and that 30 connecting leads 80 for the coils, which are attached to the stator and are not shown in

Fig. 1.A, for supplying the coils with electric power are guided through the encapsulation materia! to the outside, i.e. into the second zone 60. The electric disk motor is configured as a conveyor motor and includes an inlet 90 for a working medium and an outlet 100 for the working medium conveyed by the disk motor. As depicted in Fig. 1A, the pressure 35 inside the disk motor, p_1; differs from the pressure p₃ prevailing outside the disk motor.

Only preferably, the pressure p₁ inside the disk motor is lower than the pressure outside the disk motor Likewise, the pressure outside the disk motor may be lower than the pressure inside, i.e. within the motor housing.

In particular, it is further depicted in Fig. 1A that the rotor and the stator are arranged with5 in a motor housing 110, the motor housing comprising an opening through which the encapsulation material 70 extends The encapsulation material, or an element to which the encapsulation material is connected, is attached to the motor housing 110 by means of a schematically depicted sealing ring 120, so that there is a pressure-tight connection between the encapsulation material 70 and the motor housing 110 via the sealing ring 120, which may be an O-ring, for example. Thus, in Fig. 1A, an external-rotor motor is implemented as an exemplary electric disk motor wherein the rotor is moved inside a motor housing, whereas the coils of the stator and, in particular, that area of the stator which Is arranged at the motor gap do not communicate with the internal pressure pi of the disk motor, but communicate with the external pressure, which is particularly advantageous in terms of electrical supply of the coils typically attached within the stator, in particular when ths internal pressure p, is smaller than the external pressure p_3> the fact that the coils are not located within the low-pressure zone but are encapsulated against the low-pressure zone has considerable advantages in terms of coil breakthroughs and other effects.

Moreover, encapsulating the coils against the interior of the disk motor has advantages in that the coils do not come into contact with the medium to be conveyed and are therefore not subjected to any corrosion that might be caused by the medium to be conveyed, which medium may be water or water vapor, for example. Fig. 1A further shows that the rotor 10 is provided with permanent magnets 130 located opposite the stator-side area which typi25 cally comprises stator-side poles having magnetic coils wound thereon, so as to define the motor gap 30.

Fig. 1B shows an electric disk motor in accordance with a second aspect, which also comprises a rotor 10 located opposite a stator 20 so as to define the motor gap 30. In par30 ticular, in the second aspect shown in Fig. IB, the electric disk motor is configured to convey, by means of the element to be moved which is connected to the rotor 10 and is shown together with the rotor 10 in Fig. IB, a medium from an inlet 90, or a source zone 90, wherein a lower pressure prevails, to a target zone 100, or to an outlet 100, the target zone exhibiting a high pressure, or, generally speaking, a higher pressure than that pre35 vailing in the source zone. In addition, the electric disk motor is configured to comprise a pressure reducer 140 configured to reduce a pressure which acts upon the rotor because of the differing pressures prevailing in the source zone and in the target zone. In particular, the pressure reducer is configured such that a pressure within the motor gap 30 is smaller than the target pressure and/or than the high pressure but is higher than or equal to the source pressure. The pressure reducer 140 is therefore configured to reduce, as 5 compared to a situation where the pressure reducer is not present, the pressure prevailing within the motor gap 30 in relation to the higher pressure prevailing within the target zone and, ideally, to make it equal to the pressure prevailing within the source zone and/or to make It range between the target pressure and the source pressure.

Fig. 1C shows an alternative implementation of the electric disk motor of Fig. IB, wherein, in turn, a stator 20 is present which now forms part of the motor housing 110. The stator further is provided with coils 150 which are located opposite permanent magnets 130 of the rotor 10 so as to again form the motor gap 30. In addition, the rotor 10 is connected to an element to be moved 105 which here is configured above the rotor arid connected to the rotor. The pressure reducer 140 is provided, in turn, to reduce the pressure within the motor gap 30, specifically in relation to the pressure within the target zone, i.e. the pressure at the outlet 100.

in embodiments, a plurality of permanent magnets 130 are attached to rhe rotor 10. in addition, the stator 20 is provided with coils 150, the ceils 150 being located opposite the permanent magnets 130 located across the motor gap 30 in addition, in embodiments, each permanent magnet 130 comprises a first sector of a circle, and each pole has a second sector of a circle. The first circle sector of the permanent magnets is larger than or equal to the second circle sector of the poles. In embodiments, at least four permanent magnets which are oppositely polarized with regard to the motor gap 30 are attached to the rotor 10, the permanent magnets being polarized such that one permanent magnet has its north pole directed toward the motor gap 30 and an adjacently arranged permanent magnet has its south pole directed toward the motor gap 30.

As shown in Fig. ID, the pressure reducer 140 comprises, by way of example, a first flow resistor 140a between the target zone 100 and the motor gap 30 and a second flow resistor 140b between the motor gap 30 and the source zone 90, or outlet 90. The two flow resistors 140a, 140b are preferably both present. However, depending on the implementation, for achieving a reduction of the pressure which acts upon the rotor because of the operation of the disk armature, it may already be sufficient to provide only the first flow resistor between the target zone and the motor gap or, alternatively to the first flow resis10 tor, ίο provide the second flow resistor 140b between the motor gap and the source zone. Preferably, the first flow resistor 140a, if both flow resistors 140a, 140b are present, has a value higher than that of the second flow resistor 140b. This means that the pressure within the motor gap 30 differs from the high pressure within the target zone 100 preferably by an amount larger than that of the difference between the pressure within the motor gap 30 and the pressure within the source zone when the electric disk motor is operated.

Fig. 2A shows a preferred embodiment of the electric disk motor in accordance with the first aspect in the example of an embodiment of a radial impeller compressor which may 10 be employed with high rotational speeds of more than 50,000 revolutions per minute and up to, e g., 90,000 revolutions per minute within a neat pump which may be operated with, e.g., water as the operating medium.

Fig 2A shows an implementation of the disk motor in accordance with the first aspect, 1b wherein the stator 20 is encapsulated with the encapsulation material 70, sc that the separation of media between the high-pressure and the low-pressure zones takes place via the motor gap 40. The stator 20 is provided with coils which are not shown in Fig 2A but are already located within the ambient zone 60 which are via the access lines 80 which extend through the encapsulation material 70 and/or which, if the encapsulation material 20 encapsulates only the motor gap and parts of the stator, are already located within the ambient zone 60.

The rotor, which is formed by the permanent magnets 130, a magnetic-yoke element 160 including the permanent magnets as weil as bandage 170 attached as an additional secu25 rity measure, is further connected to the element to be moved 105, which is depicted in a merely schematic manner in Fig. 2A as a radial impeller comprising vanes. In particular, the electric disk motor is configured to rotate the radial impeller 105 and the rotor 10 within a guide element 180 which is spaced apart from the respective vane ends of the radial impeller 105 via a clearance 190. The radial impeller is configured to typically bring vapor 30 from an evaporator which has a lower pressure p₀ prevailing therein to a first pressure p,.

Said first pressure p> typically prevails at an output of the radial impeller, as is schematically shown in Fig. 2A. Typically, the guide device is coupled to a guide chamber so that the vapor, which is accelerated by the rotation of the radial impeller, is brought into the guide chamber, where it is brought to a higher target pressure p₂ because of the continu35 ing further conveyance of vapor by the radial impeller, said higher target pressure p? prevailing withm the liquefier of the heat pump, as depicted in Fig. 2A. With the external-rotor motor, the height of the electrically operative stator 20 is smaller than a diameter of the stator and is preferably smaller than half the diameter of the stator. However, when considering the internal-rotor motor, when Fig. 1C is used as a reference, the height of the electrically operative rotor in said internal-rotor motor is preferably smaller than the diame5 ter of the electrically operative rotor and is preferably even smaller than half the diameter of the rotor.

Fig. 2B shows an embodiment of the electric disk motor in accordance with the second aspect, specifically in connection with an application for a radial impeller (radial wheel) of 10 a compressor of a heat pump as depicted by means of Fig. 2A. In addition to the elements shown in Fig 2A, the two flow resistors 140a, 140b, which have been described by means of Fig. 1D, are also formed in the embodiment shown in Fig. 2'8. In particular, in the embodiment shown ·η Fig. 2B, the pressure reducer 140 includes, as an exemplary second How resistor 140b, a bore 200 within the rotor 105, said bore being configured to allow passage of media from the motor gap 40 to the source zone, or inlet, 90 into the compressor. Thus, it becomes possible to achieve passage of media through the element to be moved 105 that is connected to the rotor.

In addition, in the embodiment shown in Fig. 28, the pressure reducer 140 is configured to 20 have a plurality of constructional elements 210a. 210b, 210c which are located between the target zone, or the outlet of the radial impeller, which is also shown at 100 in Fig. 28, and the motor gap 140. Consequently, due to the interaction of the plurality of constructional elements 210a to 210c, a pressure drop from the target zone 100, which comprises a pressure p-ι, toward the motor gap is achieved, the latter comprising a pressure of p<’ only, which is smaller than the pressure ρ_Ί and is larger than or equal to the pressure p.-> in the source zone, i.e. at the inlet 90. In particular, a first constructional element of the plurality of constructional elements ss attached to the rotor. In the embodiment shown in Fig. 2B, said constructional element is the constructional element 210b. Moreover, a constructional element of the plurality of constructional elements is attached to a motor housing such as the motor housing 110. for example, said constructional element being referred to as the constructional element 210a and/or 210c. In addition, the two constructional elements which are configured as protruding rings shown in cross section in Fig. 2B are arranged to cause a pressure drop by interacting with each other. In particular, the constructional elements 210a to 210c form a labyrinth seal. In the embodiment shown in Fig. 2B, the constructional elements are each configured as a protruding ring. However, they may also be implemented as alternative constructional elements which protrude from a surface of the motor housing 110, on the one hand, and of the rotor and/or the element to be moved, on the other hand, so as to interact such that the rotor may be rotated in relation to the motor housing, and such that the close placement of the constructional elements in relation to one another causes a pressure drop, so that the pressure p-ι' within the laby5 rinth seal comprising the constructional elements 210a to 210c is smaller than the pressure pi outside the labyrinth seal.

Fig. 3 shows an alternative representation on an enlarged scale with regard to the embodiment of Fig. 28. For example, further constructional elements 212a. to 212d are config10 ured, the constructional elements 212a, 212c being arranged, in turn, on the housing 210, and the constructional elements 212b, .212d being arranged on the housing 210, or the moving element 105. in contrast to the constructional elements 210a to 210c and/or 21 Od of Fig. 3, which extend radially in relation to a rotation of the rotor, the constructional elements 212a to 212d are axially arranged in relation to a rotation of the rotor 10. in one iff- implementation, both radial and axial or alternative-orientation constructional elements or only radial constructional elements 210a to 210d or only axial constructional elements 212a to 212o or only constructional elements configured in other directions may be provided as the labyrinth seal.

In addition, it is not mandatory that in each case only a relatively small number of constructional elements as shown in Fig. 28, for example, interact with one another, but it is also possible for more or even fewer constructional elements, i.e., e.g., only two constructional elements or four or more constructional elements, to interact. In addition, it is also possible for more constructional elements to be attached to the rotor than to the housing

2.5 or vice versa.

In one implementation, the constructional elements may also be attached, between the rotor and the stator, outside the motor gap. However, in the application in Fig. 2B and/or in general it is preferred to attach the constructional elements between the rotor/the element 30 to be moved and the motor housing since in this case, the constructional elements, or the associated flow resistor R, 140a, are/is attached, between the target zone 100 and the motor gap 30. as far outside in relation to the rotor as possible, whereas the second flow resistor, i.e. the bore 200 through the rotor, is attached as far inward as possible and preferably even directly axially within the rotor. In this manner, one achieves that as large a 35 surface area as possible of the rotor, specifically at the top in the orientation depicted in

Fig. 28, which at the same time is a preferred orientation for this disk motor in one application of a heat pump compressor, is not exposed to the target pressure pi but only io the reduced pressure p<, so that on account of the operation of the rotor, which eventually results in the different pressures ρ_Ί and p_Oi nevertheless no downward deflection of the rotor, or only a very small amount of deflection, will take place. Thus, the clearance 190 5 between the guide element 180 and the radial impeller 105 may be rendered very small, so that a compressor having good efficiency will be obtained.

On the other hand, the small amount of deflection of the radial impeller in the axial direction, i.e. in the downward direction in the example shown in Fig. 213, enables the rotor to 10 be mounted by means of a magnet bearing, in particular with a magnet bearing that is passive in the axial direction, i.e. is not closed-ioop controlled in this direction but is closed-ioop controlled in the radial direction only. Thus, closed-loop control with regard to only one single, i.e the radial, direction is necessary. This leads to an electric disk motor which has a simple closed-loop bearing control concept despite the considerable rotation15 al speeds of which it is capable, since axial closed-loop bearing control is not necessary;

the rotor may nevertheless be operated with a small clearance to the guide element 180 so as to achieve high efficiency.

Fig. 4 shows a schematic representation of the forces acting upon the rotor. The rotor 10 2.0 and/or the element to be moved 105 is again schematically shown as a radial impeller in cross section; however, the individual blades are not specifically depicted for reasons of clarity but are immediately clear for persons skilled in the art. When the rotor is operated, a low evaporation pressure p₀ prevails in the source zone, whereas a higher pressure p₁is present at the output of the radial impeller in the target zone, said higher pressure ρ_Ί25 being brought to the even higher liquefier pressure through the guide chamber which the radial impeller adjoins. The output pressure ρ_Ί acts upon the upper, relatively large surface area of the radial impeller with a force F_b which is equal to the product of p_; and the surface area A,, i.e. of the surface area when the rotor 10 is seen from above.

In addition, a smaller pressure F_c acts upon the rotor from the bottom, said pressure F_obeing equal to the product of the low source pressure p, and the relatively small surface area A_o.

In addition, a weight force F_g acts upon the rotor, said weight force F_g being equal to the 35 mass of the rotor m_R times the gravitational acceleration g. In addition, a force which, in turn, acts in the upward direction is equal to a change in the mass over time multiplied by the speed of the mass flow which the radial impeller sucks in from the bottom to the top. The weight force and the force due to the mass flow are defined externally. The same goes for the dimensions of the surface areas Aq and A_b However, the pressure pi is reduced by the pressure reducer 140 in accordance with the present invention. Thus, the difference resulting from p₀-Ao-prAi is rendered as small as possible by the pressure reducer. As a result, the force which in total acts upon the rotor and/or the element to be moved on account of the operation of the rotor is reduced as far as possible, which in turn results in reduced deflection of the rotor when the rotor Is operated. When no deflection due to any contact bearing that may be present, such as a ball bearing, for example, is 10 allowed, the pressure acting upon the bearing will be reduced.

Preferably, the rotor is mounted by means of a magnetic bearing in relation to the stator, as is shown in Fig. 5 by way of example. In Fig. 5, both directions are drawn in axially 250 and radially 260. In turn, there is a motor having a motor gap 40, and the rotor is axially 15 held, in relation to the stator, because of the permanent magnets on the side of the rotor and of the electric coils on the side of the stator and is not specifically closed-loop controlled. In contrast, radial detection means 270 and radial open-loop/closed-loop control means 280 are provided. The radial detection means 270 detects the position of the rotor with regard to the stator, or vice versa, via detection lines 271 The result of the radial de20 tection 270 is communicated to the radial open-loop/closed-loop control means 280 via a sensor line 272. Said radial open-loop/closed-loop control means 280 generates corresponding actuator signals via actuator signal line 273 at the rotor and/or the stator, depending on the implementation. However, it is preferred to control the rotor only so as to position it, in relation to the stator, as a result of the actuator signal 273, such that the mo25 tor gap 40 around the complete rotor has a similar size and that the rotor does not contact the stator.

In the embodiment shown in Fig. 5, the rotor may be located on the inside, and the stator may be located on the outside. In this case, what is at hand is an internal-rotor motor.

However, alternatively, the inner element may be the stator, and the outer element may be the rotor, so that what is at hand will then be an external-rotor motor. In principle, the magnetic bearing in both cases is similar in that axial closed-loop control does not take place, whereas radial closed-loop control is effected on the part of the radial detection means 270 and the radial open-loop/closed-loop control means 280.

In embodiments, the stator is configured as a bearing stator and as a drive stator at the same time.

in addition, in embodiments, the electric disk motor is an external-rotor motor, and an axial height of the stator electrically operative for providing drive is smaller than half a diameter of the stator. In other embodiments, the electric disk motor is an internal-rotor motor, and an axial height of the rotor is smaller than half a diameter of the rotor electrically operative for providing drive, “electrically operative' referring to and being defined by the area wherein the permanent magnets used for providing drive are located, at the rotor, ορροί 0 site the coiis used for providing drive and/or the coils of the stator which are wound onto the poles.

Fig. 6 shows a cross section through a preferred rotor configured in several pieces, in particular, the rotor includes the element 105 to be moved, which In preferred embodi15 meats of the present invention is formed from a non-ferromagnetic material such as plastic or aluminum, for example. The element to be moved here is a vane wheel, or impeller, of a turbooompressor as may be applied, e.g., in a heat pump.

By contrast, the rotor 10 comprising the permanent magnets 130, the ring-shaped yoke 2(i element surrounding the permanent magnets 130, arid the bandage 170 arranged above the former, is formed of a material other than the element to be moved, in particular, the permanent magnets are formed from a specific material favorable for permanent magnets. The yoke element is annular and is formed from a ferromagnetic material, and the bandage 170 is preferably formed from a carbon material.

In the embodiment shown in Fig. 6, the permanent magnets 130 partly protrude beyond a first flat side 105a which has the recess 40 formed therein. The element to be moved 105 further has a second flat” side 105b, which, however, has a smaller diameter than the first side 105a, which may also be regarded as a flat” side when the recess 40 is considered 30 as being non-present for illustration purposes and if, further, the protrusion in the form of a revolving spring 276 is also mentally omitted. However, the spring 276 preferably engages in a ring-shaped groove 278 provided within the yoke element 160, so that the protrusion 276 and the groove 27S engage with each other. However, depending on the embodiment, also the first yoke element may have a spring provided therein, and the groove may 35 be provided within the element io be moved 105 and/or in the first flat” side 105a. Thus, the connection made of the yoke element, the permanent magnet and the bandage ob16 tains structural stability with the element to be moved 105, so that a stable overali setup is provided which retains its shape and structure even at high rotational speeds. In particular, the recess 40 further ensures that the permanent magnets and the yoke element press onto the rotor material on account of the centrifugal forces, so that the connection 5 between the yoke element, on the one hand, and the rotor material, on the other hand, is all the more tight the higher the rotational speed.

In terms of dimensions it is preferred for the motor gap 40 io be smaller than 1.5 mm; in the event of encapsulation within the motor gap, the distance between the encapsulation material and the permanent magnets is smaller than 1.5 mm. In addition, it is preferred for a diameter of the stator 20 io range from 3 cm to 7 cm or that a height of the stator be smaller than 4 cm. In addition, the electric disk motor is configured to operate at a rotational speed larger than 50,000 revolutions per minute. In addition, the bore 200 has a diameter of preferably between 1 and 4 mm. Moreover, a clearance 190 between the guide element 180 and the vane wheel 105 is preferably smaller than 1.5 mm.

As is shown in Fig. 6, in particular, it is also preferred for the element to he moved 105 to have the first ‘'flat side 105a located opposite the stator 20 and to have the second flat side 105b facing away from the stator 20, the diameter of the first flat side being larger than the second diameter of the second fiat side. As was already said, the recess 40 ,s arranged within the first flat side 105a, the permanent magnets 130 being at least partly located within the recess 40. In addition, it is useful in preferred embodiments for the yoke element to have a rather trapezoidal cross sectional shape, as shown in Fig. 6, so that an upper edge of the yoke element 160 will be arranged at a higher level, in the axial direc25 tion, than an upper edge of the permanent magnets 130. Thus, the permanent magnets

130 are arranged at as low a point as possible within the recess, whereas the yoke element protrudes beyond the permanent magnets 130 with regard to its side connected to the bandage 170.

As is shown more clearly, e.g., in Fig. 2B, the encapsulation material 70 is attached to the stator 20 not only within the motor gap 40, but also on the underside of the stator 20 in

Fig. 2B, i.e. on that side of the stator which is located opposite the recess 40. The stator here is preferably configured to be disk-shaped and has a normal which is parallel to or coincides with the axis of rotation. The fiat side of the stator is located opposite, across the recess 40, a corresponding side of the element to be moved, and the encapsulation material 70 is also attached on the flat side of the stator, in addition to the corresponding sides of the permanent magnets. However, it is not necessary for the encapsulation material to fill the entire area above the stator 20. Instead it is sufficient for the encapsulation materia! seals off the stator toward the internal area of the electric disk motor.

Fig. 7 shows a preferred application of the electric disk motor in the example of a heat pump. The heat pump includes an evaporator 300, a compressor 400 and si liquefier 500, the compressor 400 comprising the electric disk motor which was described with reference to Figs. 1A to 6. In addition to the elements of the disk motor which were depicted, e.g., with reference to Fig. 2A, the compressor further comprises a guide chamber 510 10 which is radially arranged sc· as to further convey the working vapor which has been conveyed by the element to be moved 105 and which has been sucked in by the evaporator 300. and to eventually increase the pressure up to the required pressure within the condensation zone within the condenser 500.

Liquid to be cooled passes into the evaporator via an evaporator intake 302. Cooled working liquid flows off from the evaporator via an evaporator drain 304. To ensure that the radial impeller 105 sucks m only vapor rather than water drops, a droplet separator 306 is additionally provided. Due to the low pressure prevailing within the evaporator 300, seme of the working liquid introduced into the evaporator 300 via the evaporator inlet 302 is 20 evaporated and is sucked in though the droplet separator 306 via the second side 105b of the radial impeller 105, and is conveyed upward and then discharged into the guide chamber 510 Compressed working vapor is brought into the condensation zone 510 from the guide chamber 510. The condensation zone 510 further has working liquid to be heated fed to it via a liquefier intake 512, said working liquid being heated by the heated vapor 25 by means of condensation and is discharged via a liquefier drain 514. Preferably, the liquefier is configured as a liquefier in the form of a “shower’', so that liquid distribution is achieved within the condensation zone 510 via a diffuser means 516, so that the compressed working vapor is condensed as efficiently as possible and the heat contained within it is transferred to the liquid within the liquefier.

In the embodiment shown in Fig. 7, the motor housing 110 at the same time also forms the upper housing part of the condenser, or liquefier, 500. As is further shown in Fig. 7, the connecting lead 80 for the coils of the stator 20 is connected to a controller 600 so as to perform the corresponding rotational-speed controls and, at the same time, also active 35 mounting by means of a magnetic bearing which is preferably used, as was described by means of Fig. 5. Thus, the controller additionally performs the functions of radial detection 270 and of radial open-loop/closed-ioop control 280.

Even though specific elements have been described as device elements, it shall be noted that said description is to be equally regarded as a description of steps of a method, and vice versa.

In addition, it snail be noted that the controller may be implemented as software or hardware, fur example, by the element 600 in Fig. 7 or 280 in Fig 5. The implementation of the 10 controller may be effected on a non-volatile storage medium, a digital or any other storage medium, in particular a disk or CD with electronically readable control signals which may cooperate with a programmable computer system such that the corresponding method of pumping neat and/or of operating a neat pump is performed. Generally, the invention thus also includes a computer program product having a program code, stored on a machine15 readable carrier, for performing the method, when the computer program product runs on a computer, in other words, the invention may thus also be implemented as a computer program having a program code for performing the method, when the computer program runs on a computer.

List of Reference Numerals

	10 20	rotor stator
5	30	meter gap
	40	recess
	50	first zone
	60	second zone
	70	e n ca p s u i a t i ο n m a te r i a 1
10	80	connection leads
	90	iniet/source zone
	100	outlet/target zone
	105	element to be moved
	105a	first side
15	1050	second side
	110	motor housing
	120	sealing
	130	permanent magnets
	140	pressure reducer
20	140a	first flow resistor
	140b	second flow resistor
	150	stator coils
	160	yoke element
	170	bandage
25	Ί 32 fY I Om	guide device

190 clearance

200 bore

210a-21 Ou censtructionai elements

212a-212d constructional elements

30	250	axial direction
	260	radial direction
	270	radial detection means
	’) '7' ‘	detection line
	272	control line
35	273	actuator line
	276	protrusion

278 280	groove radial open-loop/cfc
300	evaporator
302	evaporator inlet
304	evaporator drain
306	drop separator
400	compressor
410	route
500	condenser
510	condensation zone
512	liquefier inlet
514	liquefier drain
516	liquefier distributor
600	controller

Claims

1. Electric d isk motor comprising a rotor (10) comprising an element to be moved (105);

a stater (20) arranged, in relation to the rotor (10), such that a motor gap (30) is formed between the rotor (10) and the stator (20), wherein the electric disk motor is configured to convey, by means of the element to be moved (105), a medium from a source zone (90) to a target zone; (100), a target pressure within the target zone (100) being higher than a source pressure within the source zone (90), and wherein the electric disk motor further comprises a pressure reducer (140) for reducing a pressure acting upon the rotor due to the different pressures prevailing within the source zone and the target zone, the pressure reducer being configured such that a pressure with-η the motor gap (30) is smaller than the target pressure 20 and is larger than or equal to the source; pressure.

2. Electric disk motor as claimed in claim 1, wherein the pressure reducer (140) comprises a first flow resistor (140a) between the target zone (100) and the motor gap (30), or comprises a second flow resistor (140b) between the motor gap (30)

25 and the source zone (90).

3. Electric disk motor, wherein the first flow resistor (140a) and the second flow resistor (140b) are present, the first flow resistor (140a) being larger than the second flow resistor (140b).

4. Electric disk motor as claimed in any of the previous claims, wherein the pressure reducer (140) comprises a bore (200) within the rotor (10, 105) to obtain passage of media from the motor gap (30) to the source zone (90) 35 through the rotor.

5. Electric disk motor as claimed in any of the previous claims, wherein the pressure reducer (140) comprises a plurality of constructional elements (210a-210d, 210a212d) between the target zone (100) and the motor gap (30) so as to achieve, by means of the plurality of constructional elements, a pressure drop from the target

5 zone (100) to the motor gap (30), a first constructional element (210b) of the plurality of constructional elements being attached on the rotor (10) or the element to be moved (105), and a second constructional element (210a, 210c) of the plurality of constructionai elements being attached on a motor housing (110) located opposite the rotor or the element to be moved (105), the two constructional elements being 10 arranged so close to each other that together they cause a pressure drop.

6. Electric disk motor as claimed m claim 5, wherein the plurality of constructional elements (210a-210d, 212a-212d) are configured as a labyrinth seal between the rotor (10) and the motor housing (110).

7. Electric disk motor as claimed in claim 2 or 3, wherein the first flow resistor (140a) is configured as a labyrinth seal between the motor gap and the target zone (100) and wherein the second flow resistor (140b) is configured ass a bore (200) within the element to be moved (105).

8. Electric disk motor as claimed in claim 7, wherein the rotor (10) comprises, at an inner area of the recess (40), a plurality of permanent magnets (130), an annular magnetic yoke element (160) further surrounding the permanent magnets (130) so that the permanent magnets are arranged between the yoke element and the mo-

25 tor gap (30), or wherein a plurality of permanent magnets (130) are attached to the rotor (10), wherein the stator (20) is provided with coils (150), the coils (150) being located opposite the permanent magnets (130) across the motor gap (30).

9. Electric disk motor as claimed in claim 8, wherein each permanent magnet (130) includes a first sector of a circle, wherein each pole includes a second sector of a circle, and

35 wherein the first circle sector of the permanent magnets is larger than or equal to the second circle sector of the poles.

Xi

10. Electric disk motor as claimed in claim 9, wherein at least four permanent magnets which are oppositely polarized with re5 gard to the motor gap (30) are attached to the rotor (10), the permanent magnets besng polarized such that one permanent magnet has its north pole directed toward the motor gap (30) and an adjacently arranged permanent magnet has its south pole directed toward the motor gap (30).

10

11. Electric disk motor as claimed in any of the previous claims, wherein the element to be moved (105) is configured as a vane wheel connected to the rotor, the element to be moved (105) further being rotably arranged within a guide device (180), a clearance (190) between the guide element (180) and the 15 vane wheel (105) being smaller than 1.5 mm.

12 Electric disk motor as claimed in any of the previous claims, wherein the rotor (10) has a recess (40) which has the stator (20) arranged therein. 20

13. Electric disk motor as claimed in any of the previous claims, wherein the rotor is actively mounted, by means of a magnetic bearing, in a radial direction with regard to an axis of rotation of the rotor (270, 280), or

25 wherein the stator is configured as a bearing stator and as a drive stator at the same time.

14. Electric disk motor as claimed in any of the previous claims, wherein the rotor is passively mounted, by means of a magnetic bearing, in an axial direction with re-

30 gard to an axis of rotation of the rotor (10).

15. Electric disk motor as claimed in any of the previous claims, wherein the rotor (20) comprises a plurality of permanent magnets (130), a yoke 35 element (160) further being connected to the permanent magnets (130), so that the permanent magnets (130) are arranged between the yoke element (160) and the motor gap (30)

16. Electric disk motor as claimed in any of the previous claims, wherein the element to be moved (105) has a first side (105a) located opposite the stator (20), and a seco tg away from the stator, a first diameter diameter of the second side.

10

17. Electric disk motor as claimed in claim 16, wherein the first side (105a) has the recess (40) arranged therein within which the permanent magnets (130) are at least partly arranged, the permanent magnets (130) being provided, on a side facing away from the stator (20), with an annular yoke element (160)

18. Electric disk motor as claimed in claim 17, wherein the permanent magnets (130) at least partly protrude beyond the first side (105a), or wherein the annular yoke element (160) protrudes beyond the first side (105a), or wherein the permanent magnets (130) protrude by a first length beyond the first side (105a), and the annular yoke element (160) protrudes beyond the first side (105a) by a second length, which is larger than the first length, wherein the pressure reducer (140) comprises a plurality of interacting constructional elements (210a-210d, 212a-212d) for pressure reduction within an area protruding beyond the first side and located opposite a motor housing part.

Electric disk motor as claimed in any of the previous claims, wherein the element to be moved (105) is a radial impeller comprising vanes, the vanes being configured to convey, upon rotation of the radial impeller, gas to a 35 third zone having a pressure higher than the first pressure, and wherein the pressure reducer (140) comprises a bore (200) extending through the radial impeller (105) to the source zone (90).

20. Electric disk motor as claimed in claim 19, wherein the radial impeller has a first

5 side (105a) located opposite the stator(20), and a second side (105b) facing away from the stator and being arranged within the source zone (90). the pressure reducer (140) comprising the bore (200) within a centra! area of the radial impeller, and the pressure reducer (140) comprising a plurality of interacting constructional elements, at least one constructional element being configured on the rotor on the 10 first side and having a diameter larger than the first diameter.

21. Electric disk motor as claimed in claim 19 or 20, wherein the pressure reducer (140) comprises a labyrinth seal comprising at least one constructional element (210a, 210c) on a motor housing (110) and comprising the constructional element “ 5 (210b) on the rotor, which are arranged so close io each other that a pressure drop occurs via the interacting constructional elements during operation of the electric disk motor.

22. Electric disk motor as claimed in claim 20 or 21, wherein the constructional element on the rotor has a diameter which is larger than or equal to 1.75 times the first diameter.

23. Electric disk motor as claimed in any of claims 20 to 22, wherein the constructional

25 element is configured as a radially or axially extending protrusion (210a-210d,

212a-212d).

24. Electric disk motor as claimed in any of the previous claims, wherein the motor gap has an encapsulation material (70) arranged therein through which a first pressure

30 zone (50), which has the rotor (10) arranged therein, and a second pressure zone (60), which has the stator arranged therein, are separated from each other, the second pressure zone (60) differing from the source pressure or the target pressure.

35

25. Electric disk motor as claimed in any of the previous claims, the electric disk motor being an external-rotor motor, and wherein an axial height of the stator is smaller ian half a diameter of the stator, or the electric disk motor being an internal-rotor

5

26. Heat pump comprising:

an evaporator (300);

a compressor (400); and a liquefier (500), wherein the compressor (400) comprises an electric disk motor as claimed ·η any of claims 1 to 25.