GB2567581A

GB2567581A - Electric disk motor having media separation in the motor gap

Info

Publication number: GB2567581A
Application number: GB1901621.1A
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: GB201901621D0; DE102016214696A1; GB2567581B; WO2018029115A1

Abstract

The invention relates to an electric disk motor comprising: a rotor (10), which has an element (105) to be moved; and a stator (10), wherein the stator is arranged with respect to the rotor (20) in such a way that a motor gap (30) is present between the rotor and the stator, wherein the rotor (10) has a cut-out (40), in which the stator (20) is arranged, wherein the rotor (10) is arranged in a first region (50) having a first pressure, wherein the stator (20) is arranged in a second region (60) having a second pressure, wherein the second pressure differs from the first pressure, and wherein an encapsulating material (70) is arranged in the motor gap (30), by means of which encapsulating material the first region (50) is separated from the second region (60).

Description

Electric Disk Motos· with Media Separation within the Motor Gap

Description

The present invention relates to electric motors, 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 contactless manner for conveying a fluid within a pump housing inside a stator of the 10 rotary pump. In addition, the rotor is encapsulated by means of external encapsulation comprising 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 for discharging the fluid. For example, the fluid is a 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 motor without a bearing wherein the stator is formed as a bearing 20 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, “Der lagerlose Scheibenmotor (the disk motor without a bearing), N. Barletta, 1998, discloses disk, motors mounted by means of magnetic 25 bearings. Magnetic bearings operate completely tree 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 non-bearing blood pump, as a non-bearing disk motor comprising an active axial bearing, as a miniature disk motor or as a non-bearing bio reactor. By means of a 30 combination of passive reluctance magnetic bearings and a non-hearing 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 non-bearing disk motor suitable to drive an axial pump for cardiac 35 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 is characterized m 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 disk 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 is exposed to pressure differences and/or pressures acting in specific directions, irrespective of whether the rotor is designed as an internal-rotor motor or external-rotor motor. Said pressures result in that there will be a strain upon a bearing in the direction of the 15 pressure acting upon the rotor, and in that, consequently, wearing is increased, and/or in 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 2u all, expensive 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 25 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 30 claimed in claim 23, or a method of producing an electric disk motor as claimed in claim 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 35 therein. Thus, the rotor rotates around the stator. This enables that a design of the rotor may be 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 5 between the rotor and the stator, so that the entire stator is separated, in terms of media and pressure, from the zone wherein the rotor is located. Thus, ali of the coil terminals for the motor coifs 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 10 related to excess voltage and similar effects which occur when high voltages are used within 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 15 compressor element in a heat pump operating with 'water as the working medium.

However, even if 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 separation 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, 25 in particular, for high rotational speeds. The latter advantage results from the fact that permanent magnets 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 30 internal-rotor motors, to the effect that the permanent magnets there must be secured with a large 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 35 speeds of more than 50,000 revolutions per minute since in this manner the rotation of the rotor itself and/or its axis of rotation is additionally stabilized, like with a gyroscope. This effect occurs to a lesser degree, or not at 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 internal-rotor motor. It comprises a rotor having an element that is to he 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 20 between 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 25 axial terms, e.g. 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 ball bearing, the pressure reduction results in avoiding that the pressure is transferred onto the bearing and that the wear and tear of the bearing 30 increases. The pressures 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 35 very 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 tor 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 are substantially higher 5 than in 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, 10 specifically 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 the 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 15 pressure, 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 20 as large an 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 25 gap are as 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 ef 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

i?

leads io 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 disk motor comprises both encapsulation within the motor gap and the pressure reducer.

However, the two aspects maty just as well be alternatives to each other and may be employed, with regard io the pressure reducer, not only for external-rotor motors for internal-rotor motors. In addition, both aspects may also be used, separately or jointly, for contact bearings; however, utilization of rotors mounted by means of magnet bearings is preferred, in particular of axially passive bearings, i.e. axially non-closed-ioop controlled bearings and radially actively closed-loop controlled magnetic bearings

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

Fig. 1A shows an externai-rotor motor in accordance with a first aspect:

Fig. 1B 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. 1D shows a preferred implementation of the second aspect comprising two serially connected flow resistors;

ion 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 exampie 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

“V /

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

Fig. 1A 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, 15 the stator 20 being arranged, in relation to the rotor 10. such that there is 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 pi. In 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 preva Fig. 1A. By contrast, the second pressure is the a pressure, for example, when the disk pressure differing from the atmospheric

J./ or is ressure 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 30 Fig. 1A and that connecting leads 80 for the coils, which are attached to the stator and are not shown in Fig. 1A, for supplying the colls with electric power are guided through the encapsulation material to the outside, i.e. into the second zone 60. The electric disk motor is configured as a conveyor motor and includes an Intel 90 for a working medium and an outlet 100 for the working medium conveyed by the disk, motor. As depicted in Fig. 1A, the 35 pressure inside the disk motor, p_b differs from the pressure p₃ prevailing outside the disk motor. Only preferably, the pressure pi inside the disk motor is lower than the pressure · 8 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 within a motor housing 110, the motor housing comprising an opening through which the encapsulation material 70 extends. The encapsulation material· or ar> 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 10 120, 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 p, of the disk motor, but communicate With the external pressure, which is particularly 15 advantageous in terms of electrical supply of the coils typically attached within the stator.

In particular when the internal pressure p₁ is smaller than the external pressure p₃, 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 25 is provided with permanent magnets 130 located opposite the stator-side area which typically 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 30 comprises a rotor 10 located opposite a stator 20 so as to define the motor gap 30. In particular, in the second aspect shown in Fig. 1B, 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. 1B, a medium from an inlet 90, or a source zone 90, wherein a tower pressure prevails, to a target zone 100, or to an outlet 100, the target 35 zone exhibiting a high pressure, or, generally speaking, a higher pressure than that prevailing in the source zone. In addition, the electric disk motor is configured to comprise • 9 · 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 compared to a situation where the pressure reducer ss 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. 18, wherein, in turn, a stator 20 is present which now forms pari 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 15 an element to be moved 105 which here is configured above the rotor and 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 the rotor 10. in addition, the stator 20 is provided with coils 150, the coils 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 gar.) 30.

As shown in Fig. 1D, 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 35 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

- 10the first flow resistor between the target zone and the motor gap or, alternatively to the first flow resistor, to provide the second flow resistor 140b between the motor gap and the source zone. Preferably, the first How resistor 140a, if both How resistors 140a, 140b are present, has a value higher than that of the second How 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 ano the pressure Within the source zone when the electric disk motor is operated

Fig. 2A snows 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 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 heat 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, wherein the stator 20 is encapsulated With the encapsulation material 70, so 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 20 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 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 well as bandage 170 attached as an additional security 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 from an evaporator which has a lower pressure p₀ prevailing therein to a first pressure p₅. 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 · continuing further conveyance of vapor by the radial impeller, said higher target pressure p₂ prevailing within 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 diameter 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 a compressor of a heat pump as depicted by means of Fig. 2A In addition to the elements shown in Fig. 2.A, the two flow resistors 140a, 140b, which have been described by means of Fig. ID, are also formed in the embodiment shown in Fig. 28. In particular, in the embodiment shown in Fig. 28, the pressure reducer 140 includes, as an exemplary second flow 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 io the rotor.

In addition, in the embodiment shown in Fig. 2B, the pressure reducer 140 is configured to 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<, toward the motor gap is achieved, the latter comprising a pressure of p/ only, which is smaller than the pressure p? and is larger than or equal to the pressure p_Q in the source zone, i.e. at the inlet 90. In particular, a first constructional element of the plurality of constructional elements is attached to the rotor, in the embodiment shown in Fig. 28, 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 •’zseal· 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 5 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 pF within the labyrinth seal comprising the constructional elements 210a to 210c is smaller than the pressure p, outside the labyrinth seal.

Fig. 3 shows an alternative representation on an enlarged scale with regard to the embodiment of Fig. 2B. For example, further constructional elements 212a to 212d are configured, the constructional elements 212a, 212c being arranged, in turn, on the housing 210, and the constructional elements 212b, 212d being arranged on the housing 15 210. 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 implementation, both radial and axial or alternative-orientation constructional elements or only radial constructional elements 210a to 21 Od or only axial 20 constructional elements 212a to 21.2d or only constructional elements configured in other directions may be provided as the labyrinth seal.

In addition, it is not mandatory Inal in each case only a relatively small number of constructional elements as shown in Fig. 2B, for example, interact with one another, but it 25 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 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 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 35 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

- 13 ch at the same time is a preferred orientation or this disk motor in one target pressure p, but only to the reduced pressure pd, so that on account of the operation of the rotor, which eventually results in the different pressures pi and p₀, nevertheless no downward deflection of the rotor, or only a very small arnou of deflection, will take place. Thus, the clearance 190 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.

direction, i.e. in the downward direction in the example shown in Fig. 2B, enables the rotor to 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-loop controlled in this direction but is closed-loop controlled in the radial dire vIsχ..> ί >

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 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 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 25 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 pi is present at the output of the radial impeller in the target zone, said higher pressure p_;being brought to the even higher liquefier pressure through the guide chamber which the radial impeller adjoins. The output pressure p-, acts upon the upper, relatively large 30 surface area of the radial impeller with a force F_n which is equal to the product of ρ_Ί and the surface area Α_Ί, 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 35 area An.

· 14ln addition, a weight force F_g acts upon the rotor, said weight force F_g being equal to the mass of the rotor m_R times the gravitational acceleration g. in addition, a force F_M 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 A_G and A,. However, the pressure p, is reduced by the pressure reducer 140 in accordance with the present invention. Thus, the difference resulting from po-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 10 moved on account of the operation of the rotor is reduced as tar 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 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 radiaily 260. in turn, there is a motor having a motor gap 40, and the rotor is axially 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 20 controlled. In contrast, radial detection means 270 and radial open-loop/ciosed-loop control means 2S0 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 detection 270 is communicated to the radial open-loop/ciosed-loop control means 280 via a sensor line 272. Said radial open-loop/ciosed-loop control means 230 generates zb 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 motor 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 35 magnetic bearing in both cases is similar in that axial closed-ioop control does not take

- 15place, whereas radial closed-loop control is effected on the part of the radial detection means 270 and the radial open-loop/closed-ioop control means 280.

In embodiments, the stator is configured as a bearing stator and as a drive stator at the 5 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 10 an axial height of the rotor Is smaller than half a diameter of the rotor electrically operative for providing drive, “electrically operative'¹ referring to and being defined by the area ’wherein the permanent magnets used for providing drive are located, at the rotor, opposite the coils 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 embodiments of the present invention is formed from a non-ferromagnetic material such as plastic or aluminum, for exampie. The element to be moved here is a vane wheel, or 20 impeller, of a turbocompressor as may be applied, e.g., in a heat pump.

By contrast, the rotor 10 comprising the permanent magnets 130, the ring-shaped yoke element surrounding the permanent magnets 130, and the bandage 170 arranged above the former, is formed of a material other than the element to be moved in particular, the 25 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 30 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 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 35 in a ring-shaped groove 278 provided within the yoke element 160, so that the protrusion

276 and the groove 278 engage with each other. However, depending on the embodiment, also the first yoke element may have a spring provided therein, and the groove may be provided with-n the element to be moved 105 and/or in the first fiat” side 105a. Thus, the connection made of the yoke element, the permanent magnet and the bandage obtains structural stability with the element to be moved 105, so that a stable 5 overall 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 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 to 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 to range from 3 cm to 7 cm or that a height of the stator be 15 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 be 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 is arranged within the first flat side 105a, the permanent magnets 130 being at least partly 25 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 direction, 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 30 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 matenal 70 is attached to the stator 20 not only within the motor gap 40, but also on the underside of the stator 20 in 35 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 flat 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 io the corresponding sides of the permanent magnets. However, it is not necessary for the encapsulation 5 material to fill the entire area above the stator 20, Instead it is sufficient for the encapsulation material 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 10 pump. The heat pump includes an evaporator 300, a compressor 400 and a 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 5'10 which is radially arranged so as to further convey the working vapor which 15 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 20 working liquid Hows off from the evaporator via an evaporator drain 304. To ensure that the radial impeller 105 sucks in only vapor rather than water drops, a droplet separator 306 is additionally provided. Due to the low pressure prevailing within the evaporator 300, some of the working liquid introduced into the evaporator 300 via the evaporator inlet 302 is evaporated and is sucked in though the droplet separator 306 via the second side 105b 25 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 by means of condensation and is discharged via a liquefier drain 514. Preferably, 30 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,

- 18the connecting lead 80 for the coils of the stator 20 is connected to a controller 600 so as io perform the corresponding rotational-speed controls and, at the same time, also active mounting by means of a magnetic bearing which is preferably used, as was described by means of rig. 5. Thus, the controller additionally performs the functions of radial detection 5 270 and of radial open-ioop,'closed-loop control 280.

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

in addition, it shall be noted that the controller may be implemented as software or hardware, for example, by the element 600 in Fig 7 or 280 in Fig. 5. The implementation of the 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 15 which may cooperate with a programmable computer system such that the corresponding method of pumping heat and/or of operating a heat pump is performed. Generally, the invention thus also includes a computer program product having a program code, stored on a machine-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 20 as a computer program having a program code for performing the method, when the computer program runs on a computer.

- 19List of Reference Numerals

30

80

100

105

105a

105b

110

120

130

140

140a

MOb rotor stator motor gap recess first zone second zone encapsulation material connection leads inlet/source zone outlet/iarget zone element to be moved first side second side motor housing sealing permanent magnets pressure reducer first flow resistor secund flow resistor

150 stator coils

160 yoke element

170 bandage

180 guide device

190 clearance

200 bore

210a-210d constructional elements

212a-212d constructional elements

250 axial direction

260 radial direction

270 radial detection means

27!

272

273

276 detection line control line actuator line protrusion

278	groove
	280	radial open-ioop/closed-loop contro·
	300	evaporator
	302	evaporator inlet
5	304	evaporator drain
	306	drop separator
	400	compressor
	410	route
	500	condenser
10	510	condensation zone
	512	liquefier inlet
	514	liquefier drain
	516	liquefier distributor
	600	controller

Claims

1. Electric disk motor comprising:

5 a rotor (10) comprising an element to be moved (105);

a stator (20), the stator being arranged, in relation to the rotor (20), such that there is a motor gap (30) between the rotor and the stator, ranged wherein the rotor (10) is arranged within a first zone (t>0) having a first pressure, wherein the stator ¢20) is arranged within a second zone (60) having a second pressure, the second pressure differing from the first pressure, and on

A. W

2. Electric disk motor as claimed in claim 1, further comprising;

a motor housing (110) to which the encapsulation material (70) is directly or indirectly connected, so that the first zone having the first pressure is configured 25 within the motor housing and the second zone having the second pressure is configured outside the motor housing.

3. Electric disk motor as claimed in claim 1 or 2, wherein the stator (20) composes a plurality of coils (150) provided with connecting leads (80) and fitted onto onto 30 poles, the encapsulation material (70) surrounding the coils (150) and the poles, and the connecting leads (80) protruding from the encapsulation material (70) into the second zone (60), or wherein a plurality of permanent magnets (130) are attached to the rotor (10), 35 wherein the stator (20) is provided with coils (150), the coils (150) being located opposite the permanent magnets (130) across the motor gap (30).

- zz -

4. Electric disk motor as claimed In claim 3, wherein the first circle sector of the permanent magnets is larger than or the second circle sector of the poles.

5.

sk motor as claimed in claim 4 wherein 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 15 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).

6, that the first pressure is smaller than the second pressur

7.

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 io an axis of rotation of the rotor (270, 280), or wherein the stator is configured as a bearing stator and as a drive stator at the same time.

30

8. 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 regard to an axis of rotation of the rotor (10).

35

9. Electric disk motor as claimed in any of the previous claims, ί'\ '>

wherein the ises, at an in permanen magnets (130) magnetic yoke element (160) further me permanen arranged between the yoke element and the motor gap (30).

10.,

10

11.

Electric disk motor as claimed n any of the previous claims, wherein the stator (20) is disk-shaped and has a flat side whose normal is para! to or coincides with an axis of rotation, o|

V I wherein the fiat side of the stator is located opposite a side of the element to be moved (150), and (2.0) and on a front side o

12. 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

25 stator (20), and a second side (105b) facing away from the stator, a first diameter of the first side being larger than a second diameter of the second side.

13, Electric disk motor as claimed in claim 12, wherein the first side (105a) has the recess (40) arranged therein within which the permanent magnets (130) are at 30 least partly arranged, the permanent magnets (130) being provided, on a side facing away from the stator (20), with an annular yoke element (160).

14. Electric disk motor as claimed in claim 13, 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.

5 15. Electric disk motor as claimed in any of claims 12 to 14, wherein the first side (105a) composes a projection (276), and an annular yoke element (160) comprises a groove (278) configured to engage the projection (276), or the groove.

16.

Electnc disk motor as claimed in any of the previous claims.

to which the stator (20) and rhe encapsulation material (70) are connec wherein the lid is detachably connected to a motor housing part, and wherein an interface between the lid and the motor housing part has a seal (120) configured thereat by means of which the first zone (50) is sealed off from the second zone (60).

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 30 third zone having a pressure higher than the first pressure.

18. Electric disk motor as claimed in claim 15, wherein the encapsulation material (70) is arranged such that the third zone communicates with the first zone and that the first and third zones do not communicate with the second zone.

-2519. Electric disk motor as claimed in any of the previous claims, configured such that the motor gap (30) is smaller than 1.5 mm, or wherein a diameter of the stator (20) ranges from 3 cm to 7 cm, or wherein a height of the stator (20) is smaller than 4 cm, or which is configured to operate at a rotational speed higher than 50,000 rpm.

20.

being an external-rotor mo internal-rotor n axia diameter of the rotor.

wherein the rotor (10) is connected to the element to be moved (105), the element to be moved being formed of aluminum or plastic, and the rotor (10) comprising permanent magnets (130) and a magnetic yoke element (160).

/0 which is configured to convey a medium from a source zone (90) to a target zone (100) by means of the element to be moved, the pressure within (100) being higher than a pressure within rhe source zone (90), the target zone in the electric disk motor further comprising:

a pressure reducer (140) for reducing a pressure which acts upon the rotor because the rotor (10) is in operation.

23. Electric disk motor as claimed in claim 22, wherein the pressure reducer (140) comprises a first finite flow resistor (140a) between the target zone (100) and the motor gap (30) or a second finite flow resistor (140b) between the motor gap (30) and the source zone (90), wherein the first flow resistor (140a) is configured as a labyrinth seal (210a-210c) between a motor housing (110) and the rotor (10), or wherein the second flow

26 resistor (140b) is configured as a bore (200) within the rotor so that gas communication between the source zone (90) and the motor gap (30) via the bore is made possible.

5 24. Electric disk motor as claimed in claim 23. wherein the bore (200) comprises a diameter ranging from 1 to 4 mm.

Electric disk motor as claimed in any of the previous claims,

15 26. Heat pump comprising:

an evaporator (300);

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

zu

27. Heat pump as claimed in any of the previous claims, wherein the element to be moved is a vane wheel, a suction area of the evaporator (300) being connected to a guide device (180), so that during operation of the 30 electric disk motor, evaporated working liquid is sucked in, wherein during operation of the heat pump, a source pressure prevails within the suction area of the evaporator (300),

35 wherein a conveying end of the radial impeller has the first zone located thereat which exhibits the first pressure, which is higher than the source pressure, wherein the liquefier (500) exhibits a liquefier pressure which is higher than the first pressure, and wherein the second pressure within the second zone (60) is equal to the liquefier pressure or equal to an ambient pressure.

28. Method of producing an electric disk motor comprising a rotor (10) comprising an element to be moved (105), a stator (20), the stator being arranged, in relation to the rotor (20), such that there is a motor gap (30) between the rotor and the stator, the method comprising:

configuring, within the rotor (10), a recess (40) which has the stator (20) arranged therein, arranging the rotor (10) within a first zone (50) having a first pressure;

arranging the stator (20) within a second zone (60) having a second pressure, the second pressure differing from the first pressure, and arranging encapsulation material (70) within the motor gap (30) by means of which 20 the first zone (50) is separated from the second zone (60).

INTERNATIONAL SEARCH REPORT

International application No

PCT/EP2017/069851

A. CLASSIFICATION OF SUBJECT MATTER

INV. H02K21/12 H02K7/09 H02K7/14 A61M1/10 H02K5/132

ADD.

According to International Patent Classification (IPC) or to both national classification and IPC

Electronic data base consulted during the international search (name of data base and, where practicable, search terms used)

EPO-Internal, WPI Data

C. DOCUMENTS CONSIDERED TO BE RELEVANT

Category* Citation of document, with indication, where appropriate, of the relevant passages

Relevant to claim No.

WO 2008/156144 Al (PANASONIC ELEC WORKS CO LTD [JP]; FUKUDA TETSUYA [JP]; SAKAI TOSHISUKE) 24 December 2008 (2008-12-24) abstract paragraphs [0011], [0012] figure 1

JP 2006 153001 A (BRIDGESTONE CORP)

15 June 2006 (2006-06-15) abstract figure 5

1,2,4-6,

9-11,

16-21,

24-28

3,7,8,

12-15,

22,23

7,8,22,

X Further documents are listed in the continuation of Box C.

See patent family annex.

* Special categories of cited documents :

A document defining the general state of the art which is not considered to be of particular relevance

Έ earlier application or patent but published on or after the international filing date

L document which may throw doubts on priority claim(s) orwhich is cited to establish the publication date of another citation or other special reason (as specified)

O document referring to an oral disclosure, use, exhibition or other means

P document published prior to the international filing date but later than the priority date claimed

T later document published after the international filing date or priority date and not in conflict with the application but cited to understand the principle or theory underlying the invention

X document of particular relevance; the claimed invention cannot be considered novel or cannot be considered to involve an inventive step when the document is taken alone

Ύ document of particular relevance; the claimed invention cannot be considered to involve an inventive step when the document is combined with one or more other such documents, such combination being obvious to a person skilled in the art document member of the same patent family