Linear synchronous motor

Abstract

Aspects of the present disclosure relate to a linear synchronous motor, LSM. Further aspects of the present disclosure relate to a linear synchronous motor system that comprises the linear synchronous motor. In the LSM in accordance with the present disclosure, the coil winding groups and / or permanent magnets are skewed relative to the line of propagation to such an extent that deformation of the primary or secondary part can be prevented or limited.

Description

[0001] LINEAR SYNCHRONOUS MOTOR

[0002] Field

[0003] Aspects of the present disclosure relate to a linear synchronous motor, LSM. Further aspects of the present disclosure relate to a linear synchronous motor system that comprises the linear synchronous motor.

[0004] Background

[0005] LSMs are known in the art. An exemplary LSM comprises a primary part that includes a plurality of spaced apart coil winding groups. Sometimes, the primary part is referred to as the armature.

[0006] The exemplary LSM further comprises a secondary part that comprises a supporting surface, often formed by a surface of a plate made of magnetic material, on which a plurality of magnets is arranged in a spaced apart manner. Sometimes, this secondary part is referred to as reaction rail.

[0007] The primary part typically comprises a tooth member that is at least partially made of magnetic material such as iron. The tooth member comprises a tooth member base and a plurality of teeth that each extend from the tooth member base towards the secondary part. The plurality of coil windings is arranged around the teeth.

[0008] The LSM is part of an LSM system that additionally comprises an electrical driver for driving the coil winding groups for imparting a linear motion between the primary and secondary parts. For example, the electrical driver can be configured to drive the coil winding groups for generating a traveling magnet field.

[0009] Typically, the secondary part is kept stationary whereas the primary part is configured to move back and forth a line of propagation. To this end, the LSM comprises a linear guide member, such as a linear ball bearing, that limits the movement of the primary part to one degree of freedom. It should be noted that the present disclosure is not limited to embodiments in which the primary part is moving whereas the secondary part is stationary. The present disclosure equally relates to embodiments in which the primary part is kept stationary whereas the secondary part is moving, or to embodiments in which both the primary and secondary parts are moving.

[0010] In LSMs of the type described above, a strong magnetic force exists between the primary part and the secondary part. Consequently, the primary and secondary parts have one or more preferred mutual positions. Moreover, the driving force, i.e., the force responsible for the linear movement, is not constant along the travel of the LSM. This effect is known as cogging, and it limits the accuracy of the linear movement of this type of LSM. The cogging effect can be addressed by arranging the magnets in a skewed manner relative to the line of propagation. However, arranging the magnets at an angle comes at a cost as the maximum driving force is generally reduced. The Applicant has found that, due to the finite stiffness of the linear guide of LSMs and despite the known skewed arrangement of the magnets, a parasitic force or torque developed by the LSM around its lateral axis, particularly a pitch torque, may result in deformation of the system such as a deformation of the linear guide. Depending on the application and its requirements, such deformation is not acceptable.

[0011] Summary

[0012] According to an aspect of the present disclosure an LSM is provided that addresses the abovementioned problem of deformation.

[0013] In the LSM according to an aspect of the present disclosure, each coil winding group comprises multiple coil windings and has a respective first orthographic projection on the supporting surface that is elongated along a respective first axis. Furthermore, each magnet has a respective second orthographic projection on the supporting surface that is elongated along a respective second axis, wherein the plurality of magnets is regularly arranged to have a first center-to-center distance along a line of propagation.

[0014] For at least one pair of adjacent magnets among the plurality of magnets, a first magnet has a third orthographic projection of its second orthographic projection onto a first line that lies in the supporting surface and that is perpendicular to the first axes, and a second magnet has a fourth orthographic projection of its second orthographic projection onto the first line.

[0015] According to an aspect of the present disclosure, the third orthographic projection has a first overlap with the fourth orthographic projection of at least 15 percent relative to the first center-to-center distance. The first overlap can be at least 20 percent, more preferably at least 35 percent.

[0016] In some embodiments, the LSM is configured for imparting a linear motion between the primary part and secondary part back and forth along the line of propagation that is perpendicular to the first axes. In these embodiments, the coil winding groups are said to have a perpendicular orientation, but the magnets are said to have a skewed orientation.

[0017] In other embodiments, the LSM is configured for imparting a linear motion between the primary part and secondary part back and forth along the line of propagation that is perpendicular to the second axes. In these embodiments, the magnets are said to have a perpendicular orientation, but the coil winding groups are said to have a skewed orientation.

[0018] In other embodiments, the LSM is configured for imparting a linear motion between the primary part and secondary part back and forth along the line of propagation that is neither perpendicular to the second axes nor perpendicular to the first axes. In these embodiments, both the coil winding groups and the magnets are said to have a skewed orientation.

[0019] A width of the second orthographic projections along a line perpendicular to the second axes may lie in a range between 7 and 15 mm. A height of the second orthographic projections taken along a line parallel to the second axes may lie in a range between 20 and 110 mm, and a separation between adjacent second orthographic projections along a line perpendicular to the second axes may lie in a range between 1 and 7 mm.

[0020] Additionally, or alternatively, a width of the first orthographic projections along a line perpendicular to the first axes may lie in a range between 5 and 20 mm. A height of the first orthographic projections taken along a line parallel to the first axes may lie in a range between 18 and 108 mm, and a separation between adjacent first orthographic projections along a line perpendicular to the first axes may lie in a range between 1 and 15 mm.

[0021] The magnets are preferably arranged along the line of propagation with a constant separation between each pair of adjacent magnets. Similarly, the coil windings are preferably arranged along the line of propagation with a constant separation between each pair of coil winding groups.

[0022] For at least one pair of adjacent winding groups among the plurality of winding groups, a first winding group may have a fifth orthographic projection of its first orthographic projection onto a second line that lies in the supporting surface and that is perpendicular to the second axes, and a second winding group may have a sixth orthographic projection of its first orthographic projection onto the second line.

[0023] The fifth orthographic projection may have a second overlap with the sixth orthographic projection of at least 15 percent relative to the first center-to-center distance and / or at least 13 percent relative to the second center-to-center distance. The second overlap is preferably at least 20 percent, more preferably at least 35 percent, relative to the first center-to-center distance. Additionally, or alternatively, the second overlap is preferably at least 18 percent, more preferably at least 31 percent, relative to the second center-to-center distance.

[0024] In some embodiments, each coil winding of a given coil winding group may belong to a same electrical coil. For example, in some embodiments, three coil winding groups are used, wherein each coil winding group only comprises windings that belong a single electrical coil. In other embodiments, the coil windings of a given coil winding group may belong to different electrical coils. Additionally, or alternatively, the primary part may comprise a triplet of electrical coils, wherein each coil is configured to be driven separately.

[0025] The LSM may include a tooth member that comprises tooth member base and a plurality of teeth that each extend from the tooth member base towards the secondary part, wherein the plurality of coil windings is arranged around the teeth. Furthermore, the tooth member is preferably at least partially made from magnetic material, such as iron. Alternatively, in some embodiments, the primary part may comprise a solidified molding compound that mutually fixates the plurality of coil winding groups. Even in these embodiments, a skewed mutual orientation of the primary and secondary parts as described above prevents and / or limits deformation of the primary and / or secondary parts.

[0026] The LSM may further comprise a closing plate on which the plurality of magnets is mounted and of which an outer surface defines the supporting surface. The closing plate is preferably made from magnetic material. According to a further aspect of the present disclosure, a linear synchronous motor system is provided that comprises the linear synchronous motor as described above, and an electrical driver for driving the coil winding groups for imparting a linear motion between the primary part and the secondary part along the line of propagation. The electrical driver can be configured to drive the coil winding groups for generating a traveling magnet field.

[0027] Description of the drawings

[0028] So that the manner in which the features of the present disclosure can be understood in detail, a more particular description is made with reference to embodiments, some of which are illustrated in the appended figures. It is to be noted, however, that the appended figures illustrate only typical embodiments and are therefore not to be considered limiting of its scope. The figures are for facilitating an understanding of the disclosure and thus are not necessarily drawn to scale. Advantages of the subject matter claimed will become apparent to those skilled in the art upon reading this description in conjunction with the accompanying figures, in which like reference numerals have been used to designate like elements, and in which:

[0029] Figure 1 illustrates a perspective view of an LSM in accordance with an aspect of the present disclosure;

[0030] Figure 2 illustrates a top view of the LSM of figure 1 ;

[0031] Figures 3 and 4 illustrate different views of a generic orthographic projection of magnets and coil winding groups of an LSM in accordance with the present disclosure;

[0032] Figures 5 and 6 illustrate further embodiments of an LSM in accordance with the present disclosure; and

[0033] Figure 7 illustrates a linear synchronous motor system in accordance with the present disclosure.

[0034] Figure 1 illustrates a perspective view of an LSM 100A comprising a primary part 10 and a secondary part 20. Figure 2 presents a corresponding top view. LSM 100A can, just as LSM 100B and 100C to be discussed later, be part of a linear synchronous motor system 200 that is depicted in figure 7.

[0035] Primary part 10 comprises three coil winding groups 11. Each coil winding group 11 is arranged around a respective tooth 14 of tooth member 12. As shown, tooth member 12 comprises a tooth member base 13 from which teeth 14 extend towards secondary part 20.

[0036] Tooth member base 13 and teeth 14 can be made of different magnetic materials. For example, tooth member base 13 may comprise any of various types of carbon steel or electrical steel, whereas teeth 14 can be made of grain oriented or non-grain-oriented steel or cobalt iron.

[0037] Each coil winding group 11 comprises a plurality of coil windings that belong to a single electrical coil. In linear synchronous motor system 200, an electrical driver 210 is used that is capable of individually driving the three coil winding groups, indicated in figure 7 using CWG1, CWG2, CWG3. More in particular, electrical driver 210 is configured to drive the coil winding groups such that a traveling magnetic field is generated.

[0038] Secondary part 20 comprises at least a substantially flat closing plate 23 that is typically made of any of various types of carbon steel or non-grain-oriented electrical steel. A surface of closing plate 23 facing primary part 10 forms a supporting surface 21 on which a plurality of permanent magnets 22 is arranged. Magnets 22 are adjacently arranged in a direction that corresponds to a line of propagation LP. The arrangement of magnets 22 is such that the magnetic field generated by magnets 22 displays a wave-like character along line of propagation LP. For example, magnets 22 can be arranged in an alternating pole manner. For a pair of adjacent magnets 22, one magnet may have its north pole arranged facing supporting surface 21, whereas the other magnet may have its north pole arranged facing primary part 10. It should be noted that the present disclosure does not exclude other magnet arrangements such as a Halbach array.

[0039] Now referring to figure 7, when electrical driver 210 drives coil windings groups CWG1, CGW2, CWG3, a driving force is generated that causes a mutual linear motion between primary part 10 and secondary 20. Hereinafter, it will be assumed that secondary part 20 is kept stationary, while primary part 10 is allowed to move. This movement is guided by a linear guide (not shown) such as a linear ball bearing. The movement of primary part 10 is along a line of propagation, which is indicated in figure 1 using arrow LP. Furthermore, as shown in figure 1, the arrangement of magnets 22 is skewed relative to line of propagation LP.

[0040] Figures 3 and 4 present orthographic projections of magnets 22 and coil winding groups 11 onto supporting surface 21 for a general configuration of magnets 22 and coil winding groups 11. The present disclosure particularly relates to embodiments wherein magnets 22 have a substantially bar-like shape having a top and bottom surface that are both parallel to supporting surface 21, and wherein coil winding groups 11 and / or teeth 14 each have a bottom surface that is directed to and parallel to supporting surface 21. However, the present disclosure does not exclude other arrangements of magnets 22, coil winding groups 11, and teeth 14.

[0041] Figure 3 presents more details on the orthographic projection of magnets 22, whereas figure 4 presents more details on the orthographic projection of coil winding groups 11.

[0042] In figure 3, orthographic projections P2A, P2B correspond to the orthographic projections of two adjacent magnets 22 on supporting surface 21. Each orthographic projection P2A, P2B is elongated along a respective axis A2 and has a rectangular shape with a width wl and a height hl. Moreover, projections P2A, P2B have a center-to-center distance DI and are separated in a direction perpendicular to axes A2 by a distance si.

[0043] In figure 3, orthographic projections P1A, P1B correspond to the orthographic projections of two adjacent coil winding groups 11 on supporting surface 21. Each projection P1A, P1B is elongated along an axis Al and has a rectangular shape with a width w2 and a height h2. Moreover, projections Pl A, P1B have a center-to-center distance D2 and are separated in a direction perpendicular to axes Al by a distance s2. It should be noted that coil winding groups 11 typically have a rounded shape. The rectangular representation in figures 3 and 4 is therefore for illustrative purposes only and should not be construed as limiting the scope of the present disclosure. Similarly, the present disclosure is not limited to the shape of magnets 22 shown in figures 1-4.

[0044] Figure 3 further illustrates the orthographic projection of projections P2A, P2B on a line LI that lies in supporting surface 21 and that is perpendicular to axes Al. These projections, referred to as P3 and P4, display an overlap 01. Similarly, figure 4 illustrates the orthographic projection of projections P1A, P1B on a line L2 that lies in supporting surface 21 and that is perpendicular to axes A2. These projections, referred to as P5 and P6, display an overlap 02.

[0045] Due to overlap 01, when primary part 10 moves along line of propagation LP, a given coil winding group 11 will at some time be positioned above at least two magnets 22. This is counterintuitive because two neighboring magnets will have opposite polarity, so that the two flux linkages in the coil will partly cancel out and the driving force will be reduced. Depending on the dimensions and spacing of magnets 22 and coil winding groups 11 it is even possible that each coil winding group 11 will at most if not all positions along line of propagation LP be simultaneously positioned above at least two magnets 22.

[0046] According to the present disclosure, overlap 01 is substantially greater than in prior art LSMs. The Applicant has found that a large overlap 01 prevents or limits deformation of primary part 10 and secondary part 20 during operation.

[0047] In the table below, representative values for the various parameters in figures 3 and 4 are presented.

[0048] In figures 1-2, magnets 22 are skewed relative to line of propagation LP meaning that axes A2 are at an angle to line of propagation LP that is different from 90 degrees. Furthermore, coil winding groups 11 have a perpendicular orientation relative to line of propagation LP meaning that axes Al are perpendicular to line of propagation LP.

[0049] In figures 3-4, both magnets 22 and coil winding groups 11 are skewed relative to line of propagation LP. A perspective view of such arrangement is shown in figure 6. However, embodiments are also possible in which magnets 22 have a perpendicular orientation relative to line of propagation LP whereas coil windings are skewed relative to line of propagation LP. An example thereof is shown in figure 5.

[0050] The scope of the present disclosure includes any novel feature or combination of features disclosed therein either explicitly or implicitly or any generalization thereof irrespective of whether or not it relates to the claimed invention or mitigate against any or all of the problems addressed by the present invention. The applicant hereby gives notice that new claims may be formulated to such features during prosecution of this application or of any such further application derived therefrom. In particular, with reference to the appended claims, features from dependent claims may be combined with those of the independent claims and features from respective independent claims may be combined in any appropriate manner and not merely in specific combinations enumerated in the claims.

[0051] Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination.

[0052] The term “comprising” does not exclude other elements or steps, the term “a” or “an” does not exclude a plurality. Reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

CLAIMS1. A linear synchronous motor (100A; 100B; 100C), comprising: a primary part (10) comprising a plurality of spaced apart coil winding groups (11); and a secondary part (20) comprising a supporting surface (21) and a plurality of magnets (22) arranged on the supporting surface (21) in a spaced apart manner; wherein each coil winding group (11) comprises multiple coil windings and has a respective first orthographic projection (P1A, P1B) on the supporting surface (21) that is elongated along a respective first axis (Al); wherein each magnet (22) has a respective second orthographic projection (P2A, P2B) on the supporting surface (21) that is elongated along a respective second axis (A2), wherein the plurality of magnets (22) is regularly arranged to have a first center-to-center distance (D) along a line of propagation (LP); wherein for at least one pair of adjacent magnets (22) among the plurality of magnets (22), a first magnet (22) has a third orthographic projection (P3) of its second orthographic projection (P2A) onto a first line (LI) that lies in the supporting surface (21) and that is perpendicular to the first axes (Al), and a second magnet (22) has a fourth orthographic projection (P4) of its second orthographic projection (P2B) onto said first line (LI); wherein the third orthographic projection (P3) has a first overlap (01) with the fourth orthographic projection (P4) of at least 15 percent relative to the first center-to-center distance (DI).

2. The motor (100A; 100B; 100C) according to claim 1, wherein the coil winding groups (11) are adjacently arranged along the line of propagation (LP).

3. The motor (100A; 100B; 100C) according to any of the claims 1-2, wherein the first overlap (01) is at least 20 percent, more preferably at least 35 percent.

4. The motor (100A) according to any of the claims 1-3, wherein the motor (100A) is configured for imparting a linear motion between the primary part (10) and secondary part (20) back and forth along the line of propagation (LP) that is perpendicular to the first axes (Al).

5. The motor (100B) according to any of the claims 1-3, wherein the motor (100B) is configured for imparting a linear motion between the primary part (10) and secondary part (20) back and forth along the line of propagation (LP) that is perpendicular to the second axes (A2).

6. The motor (100C) according to any of the claims 1-3, wherein the motor (100C) is configured for imparting a linear motion between the primary part (10) and secondary part (20) backand forth along the line of propagation (LP) that is neither perpendicular to the second axes (A2) nor perpendicular to the first axes (Al).

7. The motor (100C) according to any of the claims 4-6, further comprising a linear guide member configured to limit mutual movement of the primary part and secondary part to one degree of freedom.

8. The motor (100A; 100B; 100C) according to any of the previous claims, wherein a width (wl) of the second orthographic projections (P2A, P2B) along a line perpendicular to the second axes (A2) lies in a range between 7 and 15 mm, wherein a height (hl) of the second orthographic projections (P2A, P2B) taken along a line parallel to the second axes (A2) lies in a range between 20 and 110 mm, and wherein a separation (si) between adjacent second orthographic projections (P2A, P2B) along a line perpendicular to the second axes (A2) lies in a range between 1 and 7 mm.

9. The motor (100A; 100B; 100C) according to any of the previous claims, wherein a width (w2) of the first orthographic projections (P1A, P1B) along a line perpendicular to the first axes (Al) lies in a range between 5 and 20 mm, wherein a height (h2) of the first orthographic projections (Pl A, P1B) taken along a line parallel to the first axes (Al) lies in a range between 18 and 108 mm, and wherein a separation (s2) between adjacent first orthographic projections (P1A, P1B) along a line perpendicular to the first axes (Al) lies in a range between 1 and 15 mm.

10. The motor (100A; 100B; 100C) according to any of the previous claims, wherein for at least one pair of adjacent winding groups (11) among the plurality of winding groups (11), a first winding group has a fifth orthographic projection (P5) of its first orthographic projection (Pl A) onto a second line (L2) that lies in the supporting surface (21) and that is perpendicular to the second axes (A2), and a second winding group has a sixth orthographic projection (P6) of its first orthographic projection (P1B) onto said second line (L2).

11. The motor (100A; 100B; 100C) according to claim 10, wherein the fifth orthographic projection (P5) has a second overlap (02) with the sixth orthographic projection (P6) of at least 15 percent relative to the first center-to-center distance (DI) and / or at least 13 percent relative to the second center-to-center distance (D2).

12. The motor (100A; 100B ; 100C) according to claim 11 , wherein the second overlap (02) is at least 20 percent, more preferably at least 35 percent, relative to the first center-to-center distance (DI) and / or at least 18 percent, more preferably at least 31 percent, relative to the second center-to- center distance (D2).

13. The motor (100A; 100B; 100C) according to any of the previous claims, wherein each coil winding of a given coil winding group (11) belongs to a single electrical coil.

14. The motor (100A; 100B; 100C) according to any of the claims 1-12, wherein the coil windings of a given coil winding group (11) belong to different electrical coils.

15. The motor (100A; 100B; 100C) according to claim 13 or 14, wherein the primary part (11) comprises a triplet of electrical coils, wherein each coil is configured to be driven separately.

16. The motor (100A; 100B; 100C) according to any of the previous claims, further comprising a tooth member (12) comprising a tooth member base (13) and a plurality of teeth (14) that each extend from the tooth member base (13) towards the secondary part (20), wherein the plurality of coil windings are arranged around the teeth (14), wherein the tooth member (12) is preferably at least partially made from magnetic material.

17. The motor (100A; 100B; 100C) according to any of the previous claims, wherein the primary part (10) comprises a solidified molding compound that mutually fixates the plurality of coil winding groups (11).

18. The motor (100A; 100B; 100C) according to any of the previous claims, further comprising a closing plate (23) on which the plurality of magnets (22) is mounted and of which an outer surface defines the supporting surface (21), wherein the closing plate (23) is preferably made from magnetic material.

19. A linear motor system (200), comprising: the linear motor (100A; 100B; 100C) as defined in any of the previous claims; an electrical driver (210) for driving the coil winding groups (11 A, 11B, 11C) for imparting a linear motion between the primary part (10) and the secondary part (20) along the line of propagation (LP).

20. The motor system (200) of claim 19, wherein the electrical driver (210) is configured to drive the coil winding groups (11 A, 1 IB, 11C) for generating a traveling magnet field.

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