A vernier machine

Abstract

A Vernier machine (1) comprising: − a first primary component (100) and a second primary component (101) which are aligned, each of the primary components (100, 101) comprising a plurality of teeth (105) and a plurality of slots (107) distributed according to an alternating arrangement; − a first multi-phase winding (103) wound about the first primary component (100) and a second multi-phase winding (113) wound about the second primary component (101); − a secondary (102) comprising a plurality of permanent magnets (104) which are mutually parallel, inclined and with alternating polarity, the secondary (102) being interposed between the first primary component (100) and the second primary component (101).

Description

[0001] DESCRIPTION A VERNIER MACHINE

[0002] Technical field

[0003] The present invention invention relates to a Vernier machine. In particular, the present invention has a great potential in low-speed applications.

[0004] The invention finds application in several sectors, such as automotive, industrial automation, ventilation, pumping, lifting machines, earthmoving, heavy agriculture, gardening, naval sector machines.

[0005] The invention may well be used in the food industry, in particular in the dairy sector, or in the chemical, pharmaceutical or cosmetic industry. The invention can be used in manufacturing areas where homogenization is a step of the production process.

[0006] Consider, for example, the production of carbon-based nanostructured materials, such as graphene and carbon nanotubes or cellular breakdown of yeasts, algae, or microorganisms for the production of intracellular material.

[0007] Background art

[0008] Beyond the numerous variants on the market, electrical machines are essentially divided into two categories, i.e. the linear and rotary ones.

[0009] A linear motor is constituted by a fixed part (the stator, also called “guide” or “track”) and by a movable part (called “mover” or “slider”) that is slidable along the fixed part.

[0010] A rotary motor is constituted by a fixed part (the stator) and by a part rotatable around its axis (the rotor).

[0011] In accordance with the established terminology, the two parts of an electrical motor may also be identified with the following terms:

[0012] - primary, where the windings are located;

[0013] - secondary, bearing the permanent magnets.

[0014] Usually, it is convenient for the primary being fixed (i.e. being the stator), and for the secondary being movable (i.e. being the mover or rotor).

[0015] However, in some solutions the primary is movable (i.e. it is the mover or rotor) and the secondary is fixed (i.e. it is the stator).

[0016] Among the electrical machines, Permanent Magnet Vernier Machines (PMVMs) gained a lot of interest over the past couple of decades. This is mainly due to their high torque density enabled by the magnetic gearing effect.

[0017] Among scientific literature, reference is made to two exemplary documents:

[0018] - A. Toba and T. A. Lipo, "Generic torque-maximizing design methodology of surface permanent-magnet vernier machine," in IEEE Transactions on Industry Applications, vol. 36, no. 6, pp. 1539-1546, Nov.-Dec. 2000, doi: 10.1109 / 28.887204;

[0019] - C. Shi, R. Qu, Y. Gao, D. Li, L. Jing and Y. Zhou, "Design and Analysis of an Interior Permanent Magnet Linear Vernier Machine," in IEEE Transactions on Magnetics, vol. 54, no. 11 , pp. 1 -5, Nov. 2018, Art no. 8106805, doi: 10.1109 / TMAG.2018.2840832.

[0020] Concerning patent literature, document US 9,595,858 discloses a rotating configuration of a double stator spoke type PMVM with a rotor core, a rotor made by permanent magnets, and two stators. Each of the two stators is separated from the rotor by an air gap.

[0021] The two stators are offset by half slot pitch for concentrating the flux from the permanent magnets in either the inner or outer stator.

[0022] Document US 10,871 ,141 discloses a linear configuration of a double stator spoke type PMVM, with a plurality of translator modules oriented in a vertical array. Despite the linear arrangment, the principle is the same as in US 9,595,858, i.e. a half slot pitch shift in order to function.

[0023] There is felt the need to increase the flux concentration.

[0024] Disclosure of the invention

[0025] In this context, the object of the present invention is to provide a Vernier machine, which overcomes the outstanding problems of the prior art cited above.

[0026] In particular, the object of the present invention is to propose a Vernier machine which increases the flux concentration effect.

[0027] The stated technical task and specified aims are substantially achieved by a Vernier machine comprising:

[0028] - a primary comprising a first primary component and a second primary component, each of said primary components comprising a plurality of teeth and a plurality of slots, distributed according to an alternating arrangement;

[0029] - a first multi-phase winding wound about the first primary component and a second multi-phase winding wound about the second primary component;

[0030] - a secondary comprising a plurality of permanent magnets, each permanent magnet being inclined with respect to a generating line of the secondary, said permanent magnets being equally distanced and distributed with alternating polarity, the secondary being interposed between the first primary component and the second primary component (101 ), a first air gap being obtained between the secondary and the first primary component and a second air gap being obtained between the secondary and the second primary component.

[0031] In particular, all the permanent magnets have a same inclination angle with respect to the generating line.

[0032] According to one aspect of the invention, the secondary comprises a plurality of grooves. Each groove houses one of the permanent magnets. Preferably, the permanent magnets are buried within the grooves.

[0033] Preferably, each groove has an elongated extension so as to receive a corresponding permanent magnet.

[0034] In particular, each permanent magnet consists of a parallelepiped block. Preferably, the number of teeth s of each primary component is chosen in combination with a pole pair number p of the corresponding multi-phase winding and the number of pairs m of permanent magnets in the secondary according to the following condition: m — s = — p Preferably, the first multi-phase winding and the second multi-phase winding are wound in the same configuration and direction.

[0035] According to one aspect of the invention, the first multi-phase winding and the second multi-phase winding are connected in series or in parallel.

[0036] Preferably, the first multi-phase winding and the second multi-phase winding are three-phase windings.

[0037] The first primary component and the second primary component are made of a ferromagnetic material. For example, the first primary component and the second primary component are made of iron-based lamination stacks.

[0038] The secondary is also made of a ferromagnetic material. For example, the secondary is made of iron-based lamination stacks.

[0039] The permanent magnets are made of one of the following: NdFeB, SmCo, Ferrite.

[0040] In a linear configuration of the Vernier machine, the secondary has a substantially parallelepiped shape with a main development axis that coincides with the generating line.

[0041] In the linear configuration, each primary component has an elongated extension with a main linear development parallel to the main development axis of the secondary.

[0042] The primary components are aligned, and the permanent magnets are mutually parallel.

[0043] The Vernier machine further comprises supporting means for the secondary.

[0044] In particular, the supporting means comprise at least two sidebars which are arranged at opposite sides of the secondary and threaded rods passing through secondary in-between the permanent magnets.

[0045] Preferably, the threaded rods are electrically isolated among each other.

[0046] In a rotating configuration of the Vernier machine, the primary components and the secondary have a hollow cylindrical symmetry and are coaxially arranged. The generating line coincides with a medium circumference of the secondary. In a preferred embodiment of the invention, the primary is a stator with the first primary component being a first stator component and the second primary component being a second stator component, and the secondary is a mover or rotor.

[0047] In another embodiment of the invention, the primary is a mover or rotor with the first primary component being a first mover component and the second primary component being a second mover component, and the secondary is a stator.

[0048] Brief description of drawings

[0049] Further characteristics and advantages of the present invention will more fully emerge from the non-limiting description of a preferred but not exclusive embodiment of a Vernier machine, as illustrated in the accompanying drawings in which:

[0050] - figure 1 illustrates a Vernier machine according to an embodiment of the present invention, in a perspective view;

[0051] - figure 2 illustrates the Vernier machine of figure 1 , where one of the shafts has been removed for the sake of comprehension;

[0052] - figure 3 illustrates the Vernier machine of figure 1 , where one of the shafts and one of the sidebars have been removed for the sake of comprehension;

[0053] - figure 4 illustrates the primary and the secondary of the Vernier machine of figure 1 , in a partially perspective exploded view;

[0054] - figure 5 illustrates the primary, the secondary and the windings of the Vernier machine of figure 1 , in a longitudinal cross-sectional view;

[0055] - figure 6 is the same as figure 5, with indication of relevant parameters;

[0056] - figure 7 illustrates a Vernier machine according to another embodiment of the present invention, in a cross-sectional view.

[0057] Detailed description of preferred embodiments of the invention

[0058] With reference to the figures, number 1 indicates a Vernier machine comprising a primary 100, 101 and a secondary 102.

[0059] The primary comprises a first primary component 100 and a second primary component 101 .

[0060] Each primary component 100, 101 comprises a plurality of teeth 105 and a plurality of slots 107 which are distributed according to an alternating arrangement. In other words, in each primary component 100, 101 a slot 107 of the plurality of slots 107 is interposed between a pair of consecutive teeth 105 of the plurality of teeth 105. Each slot 107 has a slot width s^, and each tooth 105 has a tooth width This is shown in figure 6.

[0061] A first multi-phase winding 103 is wound about the first primary component 100 and a second multi-phase winding 113 is wound about the second primary component 101 .

[0062] Preferably, the first winding 103 is a three-phase winding and the second winding 113 is a three-phase winding.

[0063] In particular, the first and the second multi-phase windings 103, 113 are wound in the same configuration and direction.

[0064] The first and the second multi-phase windings 103, 113 may be connected in series or in parallel.

[0065] The secondary 102 is arranged between the first primary component 100 and the second primary component 101 .

[0066] In particular, a first air gap 106 is obtained between the secondary 102 and the first primary component 100 and a second air gap 116 is obtained between the secondary 102 and the second primary component 101 .

[0067] The two air gaps 106, 116 are preferably of the same thickness in order to have a magnetic and force balance.

[0068] In an alternative variant, it is possible to have unequal air gaps 106, 116.

[0069] The secondary 102 comprises a plurality of permanent magnets 104 which are arranged with alternating polarity.

[0070] Each permanent magnet 104 is inclined with respect to a generating line G of the secondary 102.

[0071] In particular, all the permanent magnets 104 have the same inclination angle with respect to the generating line G. The generating line G of the secondary 102 is an imaginary line of symmetry of the secondary 102. The permanent magnets 104 are equally distanced with respect to the generating line G.

[0072] Preferably, each permanent magnet 104 consists in a block of parallelepiped shape. For example, each permanent magnet 104 is a plate-like body.

[0073] Alternatively, each permanent magnet 104 comprises a plurality of pieces. Alternatively, each permanent magnet 104 may have different shape, for example an “S” shape.

[0074] Advantageously, the secondary 102 comprises a plurality of grooves 109 for housing the permanent magnets 104. In particular, each groove 109 of the secondary 102 houses one of the permanent magnets 104.

[0075] Preferably, the grooves 109 are equally distanced, so that the permanent magnets 104 are equally distanced too. In this context, the expression “equally distanced” is referred to the generating line G or to a direction parallel to the generating line G.

[0076] According to one aspect of the invention, the grooves 9 are inclined with respect to the generating line G.

[0077] In particular, all the grooves 9 have the same inclination angle with respect to the generating line G.

[0078] Preferably, each groove 109 has an elongated extension so as to receive a corresponding permanent magnet 104.

[0079] Preferably, the permanent magnets 104 are buried within the grooves 109. This means that the permanent magnets 104 do not protrude outside the secondary 102 but are totally incorporated in the secondary 102. According to one embodiment, illustrated in figures 1 to 6, the Vernier machine 1 has a linear configuration.

[0080] In particular, the secondary 102 has a substantially parallelepiped shape with a main development axis A-A that is the generating line G.

[0081] Each primary component 100, 101 has a yoke 108 with an elongated extension which has a main linear development that is parallel to the main development axis A-A of the secondary 102.

[0082] Advantageously, the first primary component 100 and the second primary component 101 are aligned. This means that the two primary components 100, 101 are not offset or shifted with respect to each other.

[0083] Preferably, the first primary component 100 and the second primary component 101 are identical, in particular in shape and dimensions. In particular, they have the same numbers of teeth 105 and slots 107.

[0084] In particular, in each primary component 100, 101 the teeth 105 originate from the yoke 108.

[0085] According to one aspect of the invention, the grooves 9 are inclined with respect to the main development axis A-A.

[0086] An inclination angle indicated with a is defined here as the angle comprised between the main linear development of a groove 109 (which is inclined) and a line which is orthogonal to the main development axis A-A. The inclination angle a is shown in figure 6.

[0087] The grooves 109 are mutually parallel, so the permanent magnets 104 are also mutually parallel.

[0088] Preferably, the grooves 109 are equally distanced, so that the permanent magnets 104 are equally distanced too.

[0089] In particular, the permanent magnets 104 are arranged with alternating polarity within the parallel inclined grooves 109 such that there is a flux concentrating effect between two adjacent permanent magnets 104.

[0090] Other parameters of the Vernier machine 1 of the linear type, illustrated in figure 6, are defined herewith:

[0091] - permanent magnets shift xs?, is the distance between two ends of one of the grooves 109 housing the permanent magnets 104, taken along a direction that is parallel to the main development axis A-A;

[0092] - slot pitch r, is the distance between two consecutive slots 107 of one of the primary components 100, 101 ; height h of the secondary 102. The number of teeth s of each primary component 100, 101 is chosen in combination with the pole pair number p of the corresponding winding 103, 113 and the number of pairs m of permanent magnets 104 in the secondary 102, according to the condition:

[0093] ■m - ■- = ->?

[0094] In the embodiment illustrated in figure 5, for each primary component 100, 101 it is shown a distributed three-phase winding 103, 113 with p=1 placed in six slots 107 and the secondary 102 has ten permanent magnets 104 which means m = 5.

[0095] The illustrated embodiment is a mere example which may be considered as a base case. In particular, depending on the performance needs, multiple of this base case can be aligned in a modular way.

[0096] The tooth width to slot width swratio is found to be optimal with the following condition: 1.2

[0097] The inclination angle a is chosen such that the flux linked in each position by the two multi-phase windings 103, 113 is in phase.

[0098] This is verified when the permanent magnets shift to slot pitch r, ratio lies in the following range:

[0099] 0.35 0.65

[0100] Consequently, the inclination angle a can be calculated as: where h is the height of the secondary 102. In other words, the inclination angle a is chosen in relation to the height h of the secondary 102 in order to align the back electromotive force induced in the two multi-phase windings 103, 113.

[0101] In the linear configuration, the Vernier machine 1 preferably comprises supporting means for the secondary 102, which are able to transfer the thrust in a distributed manner to the external load and to be guided in the moving direction.

[0102] In the embodiment illustrated in figures 1 to 3, the supporting means comprise two sidebars 403, which are arranged at opposite long sides of the secondary 102.

[0103] The two sidebars 403 are in turn fixed to two flanges 400 located near the two opposite ends of the secondary 102.

[0104] Each flange 400 preferably houses a pair of bushes / bearings 402 to support and guide the secondary 102 through two shafts 401 .

[0105] The flanges 400, the bushed / bearings 402, and the shafts 401 also belong to the supporting means.

[0106] Furthermore, the supporting means comprise threaded rods 500 passing through each section in-between two permanent magnets 104 of the secondary 102. The threaded rods 500 are fixed to the sidebars 403, for example with nuts, as shown in figure 2.

[0107] It is recommended to have the threaded rods 500 electrically isolated among each other in order to prevent a low resistance current path.

[0108] It is extremely important that the secondary 102 is supported properly to guarantee mechanical reliability and enough stiffness to prevent the secondary from bending. The placement of the secondary 102 in the center of the two primary components 100, 102 is extremely important as the magnetic force unbalance due to eccentricity can be critical.

[0109] According to a preferred embodiment, the Vernier machine 1 is of the double stator type.

[0110] In particular, in this embodiment the primary 100, 101 is a stator and the secondary 102 is a mover. Thus, the first primary component 100 is a first stator component and the second primary component 101 is a second stator component.

[0111] In practice, the first stator component 100 and the second stator component 101 constitute the stator. This is the reason why the Vernier machine 1 is addressed here as a “double stator” Vernier machine.

[0112] The stator components 100, 101 are fixed parts, whereas the mover 102 is movable with respect to the stator components 100, 101 .

[0113] With reference to the linear configuration of the Vernier machine 1 , the mover 102 is slidable along the main development axis A-A with respect to the stator components 100, 101 .

[0114] According to an alternative embodiment, the Vernier machine 1 is of the double mover type.

[0115] In particular, in this embodiment the primary 100, 101 is a mover and the secondary 102 is a stator. Thus, the first primary component 100 is a first mover component and the second primary component 101 is a second mover component.

[0116] In practice, the first mover component 100 and the second mover component 101 constitute the mover. This is the reason why the Vernier machine 1 is addressed here as a “double mover” Vernier machine.

[0117] The stator 102 is the fixed part, whereas the mover components 100, 101 are movable with respect to the stator 102.

[0118] With reference to the linear configuration of the Vernier machine 1 , the mover components 100, 101 are slidable with respect to the stator 102.

[0119] In particular, the mover components 100, 101 are slidable along directions that are parallel to the main development axis A-A.

[0120] The proposed Vernier machine 1 can also have a rotating configuration, as shown in figure 7.

[0121] In this case, the primary components 100, 101 and the secondary 102 have a hollow cylindrical symmetry.

[0122] For example, the first primary component 100 is an outer hollow cylinder with teeth 105 and slots 107, the second primary component 101 is an inner hollow cylinder with teeth 105 and slots 107, and the secondary 102 is a hollow cylinder interposed therebetween and separated by corresponding annular air gaps 106, 116.

[0123] The primary components 100, 101 and the secondary 102 are coaxial and they have the same axis of symmetry. In practice, by unwrapping the Vernier machine 1 having a rotating configuration it is obtained a linear configuration of said machine. In the rotating configuration, the generating line G coincides with a medium circumference of the secondary 102.

[0124] The choice of the parameters for the rotary configuration is analogous to the one disclosed for the linear configuration.

[0125] The rotary configuration my by of the “double stator” type or of the “double rotor” type, in analogy with the linear configuration.

[0126] In the “double stator” type, the primary 100, 101 is a stator composed by the first primary component 100 and the second primary component 101 , and the secondary 102 is a rotor.

[0127] The rotor 102 is rotatably movable with respect to the stator components 100, 101.

[0128] In the “double rotor” type, the primary 100, 101 is a rotor and the secondary 102 is a stator. Thus, the first primary component 100 is a first rotor component and the second primary component 101 is a second rotor component.

[0129] These rotor components 100, 101 are movable with respect to the stator 102.

[0130] In particular, the first and the second primary components 100, 101 are made of a ferromagnetic material, such as iron, nickel, or cobalt in order to carry the magnetic flux through the teeth 105 and the yoke 108.

[0131] Preferably, both the primary components 100, 101 are made of iron-based lamination stacks in order to improve manufacturability and performance. The secondary 102 is also made of a ferromagnetic material. Preferably, the secondary 102 is made of iron-based lamination stacks.

[0132] The permanent magnets 104 are made of one of the following: NdFeB, SmCo, Ferrite. Alternatively, any other hard magnetic material that allows permanent magnetization can be used.

[0133] The characteristics of the Vernier machine proposed herewith emerge clearly from the above description, as do the advantages.

[0134] In particular, thanks to the specific arrangement of the permanent magnets within the grooves of the secondary (for example the rotor or mover) and thanks to their arrangement, an increased flux concentration is obtained compared to the known solutions discussed in the background.

[0135] In particular, in the linear configuration of the machine, having arranged inclined magnets in the mover / rotor adds more surface area increasing the flux concentration effect for the same mover / rotor height.

[0136] In addition, a mover / rotor iron yoke is avoided by redirecting the flux between stators.

[0137] As said in the background, known patented solutions present a spoke version which needs a half slot pitch shift in order to function, whereas the proposed invention solves the shift between the two stators, which can now be aligned.

[0138] Specifically, aligning the two primary components (for example the stators), both teeth and windings, and still having the two back electromotive force in phase, allows reaching optimal winding factor for series connection and allowing parallel connection.

[0139] In summary, the Vernier machine presented in this patent application shows a high torque / thrust density and is particularly attractive for low- speed direct drive applications.

Claims

CLAIMS1 . A Vernier machine (1 ) comprising:- a primary (100, 101 ) comprising a first primary component (100) and a second primary component (101 ), each of said primary components (100, 101 ) comprising a plurality of teeth (105) and a plurality of slots (107), distributed according to an alternating arrangement;- a first multi-phase winding (103) wound about the first primary component (100) and a second multi-phase winding (113) wound about the second primary component (101 );- a secondary (102) comprising a plurality of permanent magnets (104), each permanent magnet (104) being inclined with respect to a generating line (G) of the secondary (102), said permanent magnets (104) being equally distanced and distributed with alternating polarity, the secondary (102) being interposed between the first primary component (100) and the second primary component (101 ), a first air gap (106) being obtained between the secondary (102) and the first primary component (100) and a second air gap (116) being obtained between the secondary (102) and the second primary component (101 ).

2. The Vernier machine (1 ) according to claim 1 , wherein all the permanent magnets (104) have a same inclination angle with respect to the generating line (G).

3. The Vernier machine (1 ) according to claim 1 or 2, wherein the secondary (102) comprises a plurality of grooves (109), each groove (109) housing one of the permanent magnets (104).

4. The Vernier machine (1 ) according to claim 3, wherein said permanent magnets (104) are buried within the grooves (104).

5. The Vernier machine (1 ) according to claim 3 or 4, wherein each groove (109) has an elongated extension so as to receive a corresponding permanent magnet (104).

6. The Vernier machine (1 ) according to any one of the preceding claims,wherein each permanent magnet (104) consists of a parallelepiped block.

7. The Vernier machine (1 ) according to any one of the preceding claims, wherein the number of teeth s of each of said primary components (100, 101 ) is chosen in combination with a pole pair number p of the corresponding multi-phase winding (103, 113) and the number of pairs m of permanent magnets (104) in the secondary (102) according to the following condition: m - 5 = — p8. The Vernier machine (1 ) according to any one of the preceding claims, wherein the secondary (102) has a substantially parallelepiped shape with a main development axis (A-A) that coincides with said generating line (G), each primary component (100, 101 ) having an elongated extension with a main linear development parallel to the main development axis (A-A) of the secondary (102), said primary components (100, 101 ) being aligned and said permanent magnets (104) being mutually parallel.

9. The Vernier machine (1 ) according to claim 8, further comprising supporting means for the secondary (102).

10. The Vernier machine (1 ) according to claim 9, wherein said supporting means comprise at least two sidebars (403) which are arranged at opposite sides of the secondary (102) and threaded rods (500) passing through secondary (102) in-between the permanent magnets (104).

11. The Vernier machine (1 ) according to claim 10, wherein said threaded rods (500) are electrically isolated among each other.

12. The Vernier machine (1 ) according to any one of the claims 2 to 7, wherein said primary components (100, 101 ) and said secondary (102) have a hollow cylindrical symmetry and are coaxially arranged, said generating line (G) being a medium circumference of the secondary (102).

13. The Vernier machine (1 ) according to any one of the preceding claims, wherein said primary (100, 101 ) is a stator with said first primarycomponent (100) being a first stator component and said second primary component (101 ) being a second stator component, and the secondary (102) is a mover or rotor.

14. The Vernier machine (1 ) according to any one of the claims 1 to 12, wherein said primary (100, 101 ) is a mover or rotor with said first primary component (100) being a first mover component and said second primary component (101 ) being a second mover component, and said secondary (102) is a stator.

15. The Vernier machine (1 ) according to any one of the preceding claims, wherein the first multi-phase winding (103) and the second multi-phase winding (113) are wound in the same configuration and direction.

16. The Vernier machine (1 ) according to any one of the preceding claims, wherein the first multi-phase winding (103) and the second multi-phase winding (113) are connected in series or in parallel.

17. The Vernier machine (1 ) according to any one of the preceding claims, wherein the first multi-phase winding (103) and the second multi-phase winding (113) are three-phase windings.

18. The Vernier machine (1 ) according to any one of the preceding claims, wherein the first primary component (100) and the second primary component (101 ) are made of a ferromagnetic material.

19. The Vernier machine (1 ) according to claim 18, wherein the first primary component (100) and the second primary component (101 ) are made of iron-based lamination stacks.

20. The Vernier machine (1 ) according to any one of the preceding claims, wherein the secondary (102) is made of a ferromagnetic material.

21. The Vernier machine (1 ) according to claim 19, wherein the secondary (102) is made of iron-based lamination stacks.

22. The Vernier machine (1 ) according to any one of the preceding claims, wherein said permanent magnets (104) are made of one of the following: NdFeB, SmCo, Ferrite.