A system for cooling a high speed apparatus

Abstract

A system (1) for cooling a high speed apparatus comprising a hubless outer rotor. The system (1) is operating in a vacuum environment (3). The system comprises a stator (2) comprising a heat source, a coolant housing (4) located at least partly around the stator (2), two or more coolant chambers (5), and at least one coolant path (6) for coolant. The coolant is arranged in a direct contact with the heat source. The coolant is arranged to enter into at least one of the two or more coolant chambers (5) through an inlet (7), circulate through the at least one coolant path (6) and enter to at least one of the two or more coolant chambers (5), and exit from the at least one of the two or more coolant chambers (5) through an outlet (8). Also, a method is disclosed.

Description

[0001] A SYSTEM FOR COOLING A HIGH SPEED APPARATUS

[0002] FIELD OF THE INVENTION

[0003] The present application relates generally to a system for cooling a high speed apparatus . More specifically, the present application relates to a system for cooling a high speed apparatus comprising a hubless outer rotor .

[0004] BACKGROUND OF THE INVENTION

[0005] A high speed apparatus compris ing a rotor equipped with magnetic bearing technology may require cooling to achieve power density and efficiency . Cooling systems and materials may be however further improved .

[0006] SUMMARY

[0007] This summary is provided to introduce a selection of concepts in a s implif ied form that are further described below in the detailed description . This summary is not intended to identify key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter . The scope of protection sought for various embodiments of the present disclosure is set out by the independent claims .

[0008] Example embodiments of the present disclosure enable cooling a high speed apparatus act ing on a hubless outer rotor system operated within a vacuum with a cooling system . A vacuum envi ronment may reduce air drag of the apparatus and may significantly increase the system efficiency . However , a hi ghly power dense motor or generator may generate a lot of heat , which may be diff icult to evacuate within the vacuum . Use of the cool ing system may overcome these problems and may also have only minimal impact on the apparatus operation . This and other benefits may be achieved by the features of the independent claims . Further advantageous implementation forms are provided in the dependent claims , the description, and the drawings .

[0009] According to a first aspect a system for cooling a high speed apparatus comprising a hubless outer rotor is disclosed . The system may be arranged to operate in a vacuum environment The system may comprise a stator comprising a heat source ; a coolant housing located at least partly around the stator ; and two or more coolant chambers , and at least one coolant path for coolant . The coolant may be arranged in a direct contact with the heat source . The coolant may be arranged to enter into at least one of the two or more coolant chambers through an inlet ; circulate through the at least one coolant path; enter to at least one of the two or more coolant chambers ; and exit from the at least one of the two or more coolant chambers through an outlet . The vacuum environment may reduce air drag of the apparatus and may significantly increase the system efficiency . The system may bring a heat tran s fer path for heat elimination through a coolant . The heat transfer path may have minimal impact, on the apparatus operation . The coolant housing may comprise a coolant sleeve , upper end plate , and lower end plate .

[0010] According to an embodiment of the first aspect , the coolant housing may comprise the coolant sleeve .

[0011] According to an embodiment of the first aspect , the system may further comprise a radiator system, wherein the coolant may be arranged to flow from the outlet to the radiator system; heat from the coolant may be arranged to be extracted through the radiator system; and the cooled coolant may be arranged to be feed back to the inlet .

[0012] According to an embodiment of the first aspect , the heat source may compri se at least two end windings and a stator iron . The system may cool the stator iron and electric conductors of the end windings , for example , copper windings .

[0013] According to an embodiment of the first aspect , the stator iron may further comprise at least one winding slot , and wherein the at least one coolant path may be arranged for each winding slot . The at least one coolant path may allow cool ing of the stator iron and they may also allow flow of the coolant from the inlet cooling chamber to the outlet cooling chamber .

[0014] According to an embodiment of the first aspect , the coolant sleeve may be made of low permeabi lity and electrically low conductive material . This kind of material may have minimal effect on the magnetic flux generated in the apparatus .

[0015] According to an embodiment of the first aspect , the low permeability and electrically low conductive material may be composite . The coolant sleeve may be made of as thin material as possible to minimi ze effects on the apparatus performance . However, the material may be thick enough to bear the pressure force applied on it .

[0016] According to an embodiment of the first aspect , the system may further comprise at least one inlet channel for feeding the coolant from the inlet to the at least one coolant chamber, and at least one outlet channel for feeding the coolant from the at least one coolant chamber to the outlet . The inlet and outlet channels may facilitate transfer of the coolant .

[0017] According to an embodiment of the first aspect , a surrounding material of the at least one coolant path, the at least one inlet channel , the at least two or more coolant chambers , and / or the at least one outlet channel may be at least one of the following : steel , aluminium, plastic, and / or soft magnetic composite . These surrounding materials may be good heat conductors and resistant to pressure . The coolant may be arranged in a direct contact with the heat source , which may mean that the heat may be conducted through the surrounding material of the at least one of the following : coolant path, the at least one inlet channel , the at least two or more coolant chambers , and / or the at least one outlet channel to the coolant .

[0018] According to an embodiment of the first aspect , the at least one coolant path, the at least one inlet channel , and the at least one outlet channel may be made of one piece . One piece may decrease possible leaking points and it may also be cheaper to manufacture .

[0019] According to an embodiment of the first aspect , the at least one inlet channel , the at least one outlet channel , the two or more coolant chambers , and the at least one coolant path may be arranged to allow flow of the pressuri zed coolant . They may withstand the pressure of the coolant .

[0020] According to an embodiment of the first aspect , an air gap may be arranged between the stator and rotor to prevent collision with the coolant sleeve and to al low normal movement of the rotor . The air gap should be big enough to allow the coolant sleeve to be located between the stator and the rotor .

[0021] According to an embodiment of the first aspect , the coolant is gas or fluid . The coolant may allow heat transfer from the heat source to the coolant .

[0022] According to an embodiment of the first aspect , the system may further comprise at least one hermetically sealed feedthrough for at least one busbar . The feedthrough may make sure that the coolant may not leak into the vacuum environment .

[0023] According to an embodiment of the first aspect , heat resistant and vacuum rated adhesive may be arranged to be used in j oints of system seams . The adhes ive may be flexible enough to withstand different thermal expansion rates between bonded materials in the system . It may also have to withstand the pressure from the vacuum side . According to a second aspect a method for cooling a high speed apparatus comprising a hubless outer rotor with a system is disclosed . The system may be arranged to operate in a vacuum environment . The system may comprise a stator, which may comprise a heat source ; a coolant housing, which may be located at least partly around the stator ; and two or more coolant chambers , and at least one coolant path for coolant . The coolant may be arranged in a direct contact with the heat source . The method may comprise entering the coolant into at least one of the two or more coolant chambers through an inlet ; circulating the coolant through the at least one coolant path; and entering the coolant to at least one of the two or more coolant chambers ; and arranging the coolant to exit from the at least one of the two or more coolant chambers through an outlet . The system may bring a heat transfer path for heat elimination through a coolant . The coolant may collect heat from the heat source . The heat transfer path may have minimal impact on the apparatus operat ion .

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings , which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention . In the drawings :

[0026] Figure 1 illustrates an example of a system for cooling a high speed apparatus having a partial cross section, according to an example embodiment ;

[0027] Figure 2 illustrates an example of a cross section of figure 1 seen from a side , according to an example embodiment ;

[0028] Figure 3 illustrates an example of a partial cross section of figure 1 seen from above a stator iron, according to an example embodiment ; Figure 4 illustrates an example of a cross section of a feedthrough, according to an example embodiment ;

[0029] Figure 5 illustrates an example of a method for cooling a high speed apparatus with a system, according to an example embodiment .

[0030] Like references are used to designate like parts in the accompanying drawings .

[0031] DETAILED DESCRIPTION

[0032] Reference will now be made in detail to embod- iments , examples of which are illustrated in the accompanying drawings . The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utili zed . The description sets forth the functions of the example and the sequence of steps or operations for constructing and operating the example . However, the same or equivalent functions and sequences may be accomplished by different examples .

[0033] According to an example embodiment , a cooling system for a high speed electric apparatus act ing on a hubless outer rotor system and operated within a vacuum environment i s disclosed . The high speed apparatus may be a motor or generator . The apparatus may comprise a stator and a rotor rotating around the stator . The system may be relevant to high power density machines . The high speed rotation apparatus may have a rotor surface velocity above 150 m / s . The vacuum environment in the nigh speed electric apparatus may be crucial as i t may reduce the air drag of a rotor at high velocity and may significantly increase the system efficiency . This may bring chal lenges for heat diss ipation as the vacuum may limit heat conduction and convection due to the lack of cooling medium . According to an example embodiment, the system may compri se a coolant housing, which may separate the vacuum environment from the coolant . The coolant may be pressuri zed cool ant . Material of the coolant housing may be composite material which may have minimal effect on magnetic f lux generated in the apparatus . The coolant housing may allow direct cooling as the cool ing medium may be in direct contac t with the heat source . The cool ant or cooling medium may follow a set path : it may enter into the coolant hous ing from an inlet , may circulate to the heat source and may exit through an outlet . From the outlet the coolant may flow from to the radiator system, wherein the heat may be extracted . After that the coolant may flow’ back into the inlet .

[0034] According to an example embodiment , a system for cooling a high speed apparatus comprising a hubless outer rotor is disclosed . The system may be arranged to operate in a vacuum environment . The system may comprise a stator comprising a heat source and a coolant housing located at least partly around the stator .

[0035] According to an example embodiment , the coolant sleeve is made of low permeability and electrically low conductive material . The low permeability and electrically low conductive material may be composite . The composite material may be non-conductive or low conductive , and non-magnetic material . The non-conductive or low conductive , and non-magnetic material may comprise at least one of the following : glass fiber, carbon fiber, and / or plastic .

[0036] According to an example embodiment, the system may further comprise two or more coolant chambers and at least one coolant path for coolant . The coolant may be arranged in a direct contact with the heat source . The coolant may be arranged to enter into at least one of the two or more coolant chambers through an inlet , circulate through the at least one coolant path and enter to at least one of the two or more coolant chambers . Finally, the coolant may exit from the at least one of the two or more coolant chambers through an outlet .

[0037] According to an example embodiment , the coolant may be gas or fluid .

[0038] According to an example embodiment, the system may further comprise at least one inlet channel for feeding the coolant from the inlet to the at least one coolant chamber, and at least one outlet channel for feeding the coolant from the at least one coolant chamber to the outlet . The inlet channel may feed the coolant from the inlet to the at least one inlet side coolant chamber located at an inlet side or a bottom part of the coolant housing . The at least one outlet channel may feed the coolant from the at least one outlet side coolant chamber located at an outlet side or a top part of the coolant housing to the outlet .

[0039] According to an example embodiment , the at least one coolant path, the at least one inlet channel , the at least two or more coolant chambers ( 5 ) , and / or the at least one outlet channel comprise a surrounding material inside of which the coolant flow . According to an example embodiment , the surrounding material of the at least one coolant path, the at least one inlet channel , the at least two or more coolant chambers ( 5 ) , and / or the at least one outlet channel is at least one of the following : steel , aluminium, plastic, and / or soft magnetic composite .

[0040] According to an example embodiment , the at least one coolant path, the at least one inlet channel , and the at least one outlet channel are made of one piece . The one piece may decrease possible leaking points . I f more parts are used it may increase costs and possibility that seams may leak .

[0041] According to an example embodiment , the at least one inlet channel , the at least one outlet channel , the two or more coolant chambers , and the at least one coolant path are arranged to allow flow of the pressuri zed coolant . Coolant pressure may not be static . There may be pressure difference between the inlet and the outlet .

[0042] According to an example embodiment, the heat source comprises at least two end windings and a stator iron . Purpose of the system may be to cool the electric conductors of the at least two end windings , for example , copper windings , which may be the heat sources with the stator iron . At least one of the at leas t two end windings may be located in the inlet side coolant chamber . At least one of the at leas t two end windings may be located in the out let side coo lant chamber .

[0043] According to an example embodiment , the stator iron further comprises at least one winding slot , and wherein the at least one coolant path is arranged for each winding slot . The number and location of the winding slots , and also dimensions of the slots may be at the discretion of the designer .

[0044] According to an example embodiment, the system further comprises a radiator system . The coolant may be arranged to flow from the outlet to the radiator system, wherein heat from the coolant may be arranged to be extracted through the radiator system . Finally, the cooled coolant may be arranged to be feed back to the inlet .

[0045] According to an example embodiment , an air gap is arranged between the stator and rotor to prevent collision with the coolant sleeve and to allow normal movement of the rotor . Si ze of the air gap may depend on the electromagnetic design of the system . The air gap between the stator and rotor is from 1 mm to 10 mm, for example .

[0046] According to an example embodiment, the system further comprises at least one hermetically sealed feed- through for at least one busbar . A number of the feedthroughs may match to a number of phases of the apparatus , such as a motor or a generator . The system may have three feedthroughs , for example .

[0047] According to an example embodiment , heat resistant and vacuum rated adhes ive is arranged to be used in j oints of system seams . The adhesive may be epoxy glue . The adhesive may be flexible enough to withstand different thermal expansion rates between bonded materials in the system . It may also have to withstand the pressure from the vacuum side .

[0048] An example of Figure 1 i llustrates a system 1 for cooling a high speed apparatus having a partial cros s section . Figure 2 il lustrates a cross section of figure 1 seen from a side . The apparatus may be a high speed apparatus comprising a hubless outer rotor and the system 1 . For clarity reasons the rotor is not shown in the figure 1 . The system 1 may comprise a stator 2 comprising a heat source . The system 1 may also comprise a coolant housing 4 located at least partly around the stator 2 and two or more coolant chambers 5 , and at least one coolant path 6 for coolant . The coolant housing 4 may comprise a coolant sleeve 9 , upper end plate 10 , and lower end plate 11 . The system 1 may be arranged to operate in a vacuum environment 3 . The system 1 may be separated from the rotor by a gap, which has the vacuum environment 3 . The coolant sleeve 9 may be located between the stator 2 and the rotor .

[0049] The two or more coolant chambers 5 may comprise at least one coolant chamber 5 arranged in an inlet side or a bottom part of the coolant hous ing 4 and at least one coolant chamber 5 arranged in an outlet side or a top part of the coolant housing . The coolant may be arranged in a direct contact with the heat source . The heat source may comprise at least two end windings 12 and a stator iron 16 .

[0050] The coolant flow 15 may be arranged to enter into at least one of the two or more coolant chambers 5 through an inlet 7 and circulate through the at least one coolant path 6 and enter to at least one of the two or more coolant chambers 5 . Finally, the coolant may exit from the at least one of the two or more coolant chambers 5 through an outlet 8 .

[0051] According to an example embodiment , the system 1 further comprises at least one inlet channel 18 for feeding the coolant from the inlet 7 to the at least one coolant chamber 5 , and at least one outlet channel 19 for feeding the coolant from the at least one coolant chamber 5 to the outlet 8 . The at least one inlet channel

[0052] 18 may be located between the inlet 7 and the at least one coolant chamber 5 . The at least one outlet channel

[0053] 19 may be located between the outlet 8 and the at least one coolant chamber 5 .

[0054] According to an example embodiment, the system 1 may further compri ses a radiator system . The coolant may be arranged to flow from the outlet 8 to the radiator system and heat from the coolant may be arranged to be extracted through the radiator system . At the end, the cooled coolant may be arranged to be feed back to the inlet 7 .

[0055] According to an example embodiment, the stator iron 16 further comprises at least one winding slot 17 . The at least one coolant path 6 may be arranged for each winding slot 17 . The at least one coolant path 6 may be located radially around the stator iron 16 . An example of figure 1 comprises two coolant paths 6 for each winding slot 17 . The two coolant paths 6 for each winding slot 17 may be located at the inner and outer ends of each winding slot 17 . The at least one coolant path 6 of figure 1 example may be located at least partly inside the stator iron 16 . They will lead the coolant from the inlet side coolant chamber 5 to the outlet side coolant chamber 5 .

[0056] The system 1 may further comprise a lower feed- through body 13 and an upper feedthrough body 14 . The at least one inlet channel 18 and the at least one outlet channel 19 may be located inside the lower feedthrough body 13 and the upper feedthrough body 14 , respectively .

[0057] According to an example embodiment , the at least one coolant path 6 , the at least one inlet channel 18 , and the at least one outlet channel 19 are made of one piece .

[0058] According to an example embodiment , the system comprises two coolant paths 6 for each winding slot 17 .

[0059] According to an example embodiment , the at least one coolant path 6 is located at least partly inside the stator iron 16 .

[0060] An example of figure 3 illustrates a partial cross section of figure 1 seen from above the stator iron 16 . An example of figure 3 comprises two coolant paths 6 for each winding slot 17 and the coolant sleeve 9 is arranged around the stator iron 16 . The example shows that the two coolant paths 6 for each winding slot 17 are located at the inner and outer ends of each winding slot 17 .

[0061] An example of figure 4 illustrates a cross section of a feedthrough 20 for a busbar 21 . The at least one hermetically sealed feedthrough 20 may be located between the coolant chamber 5 and the vacuum environment 3 of the system 1 . The at least one feedthrough 20 may allow the busbar 21 to go through a wall of the cooling chamber 5 . The feedthrough may make sure that the coolant may not leak into the vacuum environment 3 . A number of the feedthroughs 20 may match to a number of phases of the apparatus . The system may have three feedthroughs , for example .

[0062] According to an example embodiment , heat resistant and vacuum rated adhes ive is arranged to be used in j oints of system seams . The adhesive may be epoxy glue . The adhesive may be flexible enough to withstand different thermal expansion rates between bonded materials in the system . It may also have to withstand the pressure from the vacuum environment 3 . The adhesive may be used also with seams of the feedthrough 20 .

[0063] Figure 5 illustrates an example of a method for cooling a high speed apparatus with a system 1 . The system 1 may be arranged to operate in a vacuum environment 3 . The system 1 may further comprise a stator 2 comprising a heat source , a coolant housing 4 located at least partly around the stator 2 , and two or more coolant chambers and at least one coolant path 6 for coolant . The coolant may be arranged in a direct contact with the heat source .

[0064] At operation 500 , the method may comprise entering the coolant into at least one of the two or more coolant chambers 5 through an inlet 7 .

[0065] At operation 510 , the method may comprise circulating the coolant through the at least one coolant path 6 and entering the coolant to at least one of the two or more coolant chambers 5 .

[0066] At operation 520 , the method may comprise arranging the coolant to exit from the at least one of the two or more coolant chambers 5 through an outlet 8 .

[0067] Further features of the method directly result from functionalities of , for example , the system 1 . Different variations of the method may be also applied, as described in connection with the various embodiments .

[0068] The system 1 may be configured to perform or cause performance of any aspect of the method described herein .

[0069] Any range or device value given herein may be extended or altered without losing the effect sought . Also , any embodiment may be combined with another embodiment unless explicitly disallowed .

[0070] Although the subj ect matter has been described in language specific to structural features and / or acts , it is to be understood that the subj ect matter defined in the appended claims is not necessarily limited to the specific features or acts described above . Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims .

[0071] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages . It wil l further be understood that reference to ' an ' item may refer to one or more of those items .

[0072] The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate . Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subj ect matter described herein . Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought .

[0073] The term ' comprising ' is used herein to mean including the method, blocks , or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements .

[0074] Although subj ects may be referred to as ' first , ' second' , or ' third' subj ects , this does not necessarily indicate any order or importance of the subj ects . Instead, such attributes may be used solely for the purpose of making a difference between subj ects .

[0075] It will be understood that the above description is given by way of example only and that various modif ications may be made by those s kil led in the art . The above specification, examples and data provide a complete description of the structure and use of embodiments . Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments , those skilled in the art could make numerous alterations to the disclosed embodiments without departing from scope of this specification .

Claims

CLAIMS1. A system (1) for cooling a high speed apparatus comprising a hubless outer rotor, wherein the system (1) is arranged to operate in a vacuum environment (3) , the system comprising a stator (2) comprising a heat source; a coolant housing (4) located at least partly around the stator (2) ; and two or more coolant chambers (5) and at least one coolant path (6) for coolant, wherein the coolant is arranged in a direct contact with the heat source, wherein the coolant is arranged to enter into at least one of the two or more coolant chambers (5) through an inlet (7) ; circulate through the at least one coolant path (6) and enter to at least one of the two or more coolant chambers (5) ; and exit from the at least one of the two or more coolant chambers (5) through an outlet (8) .

2. The system (1) according to claim 1, wherein the system further comprises a radiator system, wherein the coolant is arranged to flow from the outlet (8) to the radiator system; heat from the coolant is arranged to be extracted through the radiator system; and the cooled coolant is arranged to be feed back to the inlet ( 7 ) .

3. The system (1) according to claim 1 or claim 2, wherein the heat source comprises at least two end windings (12) and a stator iron (16) .

4. The system (1) according to claim 3, wherein the stator iron (16) further comprises at least onewinding slot (17) , and wherein the at least one coolant path (6) is arranged for each winding slot (17) .

5. The system (1) according to any one of the preceding claims, wherein the coolant sleeve (9) is made of low permeability and electrically low conductive material .

6. The system (1) according to claim 5, wherein the low permeability and electrically low conductive material is composite.

7. The system (1) according to any one of the preceding claims, wherein the system further comprises at least one inlet channel (18) for feeding the coolant from the inlet (7) to the at least one coolant chamber(5) , and at least one outlet channel (19) for feeding the coolant from the at least one coolant chamber (5) to the outlet ( 8 ) .

8. The system (1) according to claim 7, wherein a surrounding material of the at least one coolant path(6) , the at least one inlet channel (18) , the at least two or more coolant chambers (5) , and / or the at least one outlet channel (19) is at least one of the following: steel, aluminium, plastic, and / or soft magnetic composite.

9. The system (1) according to claim 7 or claim 8, wherein the at least one coolant path (6) , the at least one inlet channel (18) , and the at least one outlet channel (19) are made of one piece.

10. The system (1) according to any of claims 7 to 9, wherein the at least one inlet channel (18) , the at least one outlet channel (19) , the two or more coolantchambers (5) , and the at least one coolant path (6) are arranged to allow flow of the pressurized coolant.

11. The system (1) according to any one of the preceding claims, wherein an air gap is arranged between the stator (2) and rotor to prevent collision with the coolant sleeve (9) and to allow normal movement of the rotor .

12. The system (1) according to any one of the preceding claims, wherein the coolant is gas or fluid.

13. The system (1) according to any one of the preceding claims, wherein the system (1) further comprises at least one hermetically sealed feedthrough (20) for at least one busbar (21) .

14. The system (1) according to any one of the preceding claims, wherein heat resistant and vacuum rated adhesive is arranged to be used in joints of system seams .

15. A method for cooling a high speed apparatus comprising a hubless outer rotor with a system (1) , wherein the system (1) is arranged to operate in a vacuum environment (3) , the system comprising a stator (2) comprising a heat source; a coolant housing (4) located at least partly around the stator (2) ; and two or more coolant chambers (5) and at least one coolant path (6) for coolant, wherein the coolant is arranged in a direct contact with the heat source, wherein wherein the method comprising entering (500) the coolant into at least one of the two or more coolant chambers (5) through an inlet (7) ;circulating (51 ) the coolant through the at least one coolant path ( >) and entering the coolant to at least one of the two or more coolant chambers (5) ; and arranging (520) the coolant to exit from the at least one of the two or more coolant chambers (5) through an outlet (8) .

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