ELECTRIC MOTOR

Description

[0001] The invention relates to an electric motor with a magnetic track comprising a plurality of magnetic elements arranged in a longitudinal direction, in particular in a Halbach array configuration, and a coil arrangement comprising a carrier configured in such a way that the coil arrangement is capable of guided movement relative to the stator magnetic track and comprising at least one group of three conductive flat coils.

[0002] Linear actuators have been gaining increasing importance in a wide variety of industrial applications for decades. They are therefore the subject of extensive development work, a significant portion of which aims at the most efficient and thus cost-effective manufacturing possible while ensuring high performance.

[0003] Linear motors typically comprise several coils or coil sets arranged adjacent to one another, and a plurality of magnets arranged with their north and south poles alternating along a magnetic track. Successive excitation of the coils by an electric current causes the coil arrangement to move relative to the magnet arrangement, i.e., along the magnetic track.

[0004] While the aforementioned coils are typically constructed from wound wires, efforts have been underway for several years to develop a simpler manufacturing method using so-called flat coils. These developments are driven in particular by the need for smaller and even miniaturized linear motors, where the conventional method of coil manufacturing becomes increasingly uneconomical as the dimensions decrease and could ultimately represent a limiting factor for the use of linear actuators.

[0005] A linear motor with this novel design is described in US 6,664,664 B2. Here, flat coils are arranged side-by-side on an elongated, non-conductive substrate and connected to the different phases of a multi-phase power supply. The publication also describes the multi-layered construction of each flat coil by means of essentially identical conductor paths arranged one above the other in several conductor layers of a multi-layer printed circuit board. The geometric configuration of these flat coils is that of a rectangle, and connection areas are arranged outside each rectangle, encompassing vias through the multi-layer printed circuit board.

[0006] A multi-layer flat coil arrangement is also known from WO 2017 / 080859 A1 of the applicant, namely as a component of a planar positioning device or a positioning table. Here, too, a multi-layer printed circuit board is used for the technical implementation, wherein several related flat coils are implemented as conductor traces of a first conductor layer of the multi-layer printed circuit board for most of their length, and crossing areas of the flat coils run essentially in a second conductor layer of the multi-layer printed circuit board. Further relevant prior art is provided by US 2002 / 185919 A1 and EP 0 133 571 A2.

[0007] The invention is based on the objective of providing an improved electric motor which is characterized, among other things, by increased efficiency in compact dimensions and can be manufactured efficiently and cost-effectively.

[0008] This problem is solved by an electric motor having the features of claim 1. Advantageous further developments of the inventive concept are the subject of the dependent claims.

[0009] The invention includes the concept of nesting several (in practice, specifically three) flat coils, each connected to one of the individual phases of a multi-phase power supply (specifically, a three-phase network), within one another to optimally utilize the available conductor area of ​​a first and second conductor plane on a non-conductive substrate. This necessarily results in certain conductor sections of the multiple flat coils overlapping or crossing each other. The aforementioned nesting is geometrically determined with respect to the two available conductor planes such that at any given point, conductor traces from at most two of the three flat coils lie one above the other. In those areas, which are subsequently referred to as crossing areas, the conductor traces of one of the two flat coils are formed in only one of the two conductor planes, while the (crossing or crossing)Overlapping conductor traces of the other flat coil run in the other of the two conductor planes. However, in all those sections of the nested flat coils where no conductor traces of two coils cross, both conductor planes are used for overlapping conductor traces of one of the three flat coils.

[0010] Both the concept of nesting (instead of placing side by side) the flat coils belonging to the same group within the multi-phase supply scheme and the use of large areas of both conductor planes above and below the insulating intermediate layer for the execution of the conductor traces of each of the flat coils lead to a significantly improved utilization of the available conductor area, and the concept also offers the possibility of a much more compact design of the flat coil group as a whole and thus possibly also of the linear motor as a whole.

[0011] Furthermore, the arrangement of nested coils results in a homogenization of the force constants in the longitudinal direction of the carrier, and it enables the use of improved magnet arrangements that do not require magnetic feedback and can therefore be made lighter and more compact, especially so-called Halbach arrangements.

[0012] According to the invention, the magnetic track with the series of magnetic elements and the flat coils of the coil arrangement are dimensioned in such a way that the crossing areas of the flat coils lie at least predominantly outside the projection of the magnetic elements onto the coil arrangement. Inhomogeneities of the magnetic field induced by the coils in the crossing areas thus remain largely outside the area of ​​interaction with the magnets, thereby largely preventing disturbances in the force constant.

[0013] In a practically significant embodiment, the magnetic track is assigned to a stator and the coil assembly to a rotor of the linear motor. For example, the stator essentially has the shape of an elongated U-profile, and the rotor, adapted to the shape of the U-profile, is designed as a plate or strip such that it can move along the inside of the U-profile. This is the predominant design of a linear motor; however, it should be noted that the assignment of magnets and coil assembly to stator and rotor can also be reversed. It is also not essential that the stator has the shape of a U-profile and the rotor a plate or strip. Rather, other geometric configurations, such as with T- or double-T-profiles, are also possible.The required precise spacing between two magnet arrangements, which together form a magnetic track and between which a coil arrangement is mounted as a rotor, can also be ensured by end spacers. Such a stator would have the shape of an elongated rectangle in longitudinal section, with the two magnet arrangements located along its long sides.

[0014] In further embodiments of the invention, the coil arrangement comprises two or more groups of three flat coils each connected to one phase of a three-phase power supply, and the dimensioning of the coil arrangement (in particular as rotor) and the magnetic track (in particular as stator) is adapted to the specific application and its boundary conditions and parameters, in particular the required path length, the force to be applied by the motor, the available installation space, etc.

[0015] In a technologically and therefore cost-effective implementation, the carrier is designed as a multi-layer printed circuit board. Exactly two adjacent conductor layers ("first" and "second" conductor layer) of the multi-layer printed circuit board are structured to form the three corresponding, overlapping flat coils. The technology for structuring multi-layer printed circuit boards, as well as the technology for creating connections between the different conductor layers by means of vias, with selective connection of the vias to the respective conductor tracks in the individual conductor layers, are established, reliable, and cost-effective technologies that can readily be used to manufacture the coil arrangement according to the invention. The associated design methods are also available.

[0016] The following are some of the key advantages: Minimizing the development time of new engine sizes through suitable software interfaces and due to multiple uses of design elements and high repeatability of assemblies, simple manufacturing, short delivery times, low manufacturing effort and strong cost reductions, especially for high production volumes.

[0017] The use of special magnet arrangements (especially in an elongated stator) that is possible in connection with the invention provides, among other things, the following further advantages: This design enables the implementation of a single-sided magnet arrangement relative to the coil assembly, which in turn allows for a particularly flat construction. The elimination of a magnetic backplate allows the magnet carrier to be manufactured from a lightweight, non-conductive material. This also reduces stray magnetic fields. Compared to conventional magnet arrangements with alternating north / south orientation, higher magnetic field strengths are achievable.

[0018] In one embodiment of the latter design, the carrier is designed as a multi-level printed circuit board with 2m conductor levels (m≥2), in which each of the three related overlapping flat coils of a group comprises 2 to m essentially identical conductor traces connected in series, wherein the electrical connections between the conductor traces connected in series are made by means of vertical vias through the multi-level printed circuit board.

[0019] In a further embodiment of the invention, each of the flat coils has a small connection and via area located directly on an outer surface of the respective flat coil. This connection and via area includes not only the external connections but also vias for connecting the superimposed, series-connected conductor tracks and for the external connection of the flat coil. It should be noted that the aforementioned connection and via area on an outer edge of a flat coil typically does not include all, but only a portion of all vias in the coil assembly. Further vias are required at the intersection areas, according to the features of the invention described above.In one embodiment, the small connection area is positioned near a corner of an essentially rectangular flat coil configuration, and it includes a hook-shaped conductor section.

[0020] In a further embodiment of the invention, the three related flat coils formed by structuring the two conductor levels of the multi-level printed circuit board are essentially configured in a rectangular shape and are nested or overlapped in such a way that the long sides of the rectangular conductor configurations in the first and second conductor levels run parallel to each other and within the rectangle of one of the three flat coils the largest part of the conductor path of each long side of the other two flat coils is arranged.

[0021] Related to this is the aspect that all conductors of the three flat coils are equidistant from each other along the long sides of the rectangular conductor configurations, and that no significant spacing exists within the three associated flat coils. In a further embodiment, the distance between adjacent conductor strands is less than their width, in particular less than half their width.

[0022] In particular, the latter aspects enable the efficient utilization of the conductor areas on or within the support of the coil assembly, as mentioned above, through the nested or overlapping arrangement of the flat coils assigned to the individual fibers. Unlike the prior art mentioned at the beginning, practically no conductor area remains within a coherent coil group that is not physically used for the conductor traces of a flat coil.

[0023] A geometrically appropriate configuration for realizing the nesting or overlapping according to the invention provides that in the essentially rectangular conductor path of the flat coils, one (virtual) corner of the rectangle is replaced by conductor sections running obliquely to the short and long sides. In the design, this is specifically implemented such that the obliquely running conductor sections of the three related, overlapping flat coils adjoin each other and run nested within each other in the first and second conductor planes, becoming progressively shorter towards the center of the respective rectangle.

[0024] In a further embodiment of the invention, at least a portion of the conductor paths is widened, at least in part of the crossing areas. Due to the reduced current load resulting from the widening, the widened sections of the conductor paths act as temperature sinks for the respective flat coil. This absorbs temperature increases in other sections of the conductor paths, which, due to the design, cannot be widened and therefore exhibit greater heating due to the increased current load.

[0025] Further advantages and expedients of the invention will become apparent from the following description of exemplary embodiments or aspects with reference to the figures. These show: Fig. 1 a schematic perspective view of a linear motor of the type according to the invention, Figs. 2A to 2C schematic perspective views of another linear motor of the type according to the invention, Fig. 3 a schematic view of the magnetic pole alignment in the magnetic track of a linear motor of the type according to the invention. Fig. 1 or 2 Fig. 4 shows the conductor paths of a flat coil group consisting of three related flat coils, which are nested or overlapped according to the invention in or on a support, Fig. 5 shows the associated conductor traces in a first and a second conductor plane of the support, Fig. 6 shows the coil group with the three nested or overlapping flat coils, Fig. 7 shows a schematic representation of several flat coils arranged one after the other on a support and realized in several support layers one above the other. Fig. 6 The structure shown, Fig. 8, is a schematic representation of a multi-level printed circuit board in which the coil arrangement is shown according to Fig. 7 As realized, Fig. 9 shows a schematic representation of the coil arrangement. Fig. 7 in relation to the magnetic track of a linear motor, as in Fig. 1 or 2 shown, and Fig. 10 a schematic perspective view of another electric motor of the type according to the invention.

[0026] Fig. 1 Figure 1 schematically shows the main component of an electric linear motor 1, namely an elongated, ribbon-shaped arrangement 3 of closely spaced, rod-shaped permanent magnets 31, and a plate-shaped coil arrangement 5, which comprises an arrangement of flat coils 51 aligned in the same direction as the permanent magnets. Normally, the magnet arrangement 3, together with an associated support structure, forms the stator of the linear motor, while the coil arrangement 5 forms its rotor. As is already evident from the schematic representation, the stator / rotor functions can also be kinematically reversed, which is why, in the following and in the claims, the magnet arrangement is also referred to as the "magnetic track" and the array of flat coils as the "coil arrangement".In a known manner, a movement of the rotor along the stator is caused by a sequential excitation of the flat coils connected to different phases of a multiphase power supply (see below) and the sequential build-up of corresponding magnetic fields.

[0027] Fig. 2A bis 2C show modified versions of the linear motor which - with otherwise identical construction - comprise a magnetic track 3' made up of two superimposed band-shaped magnet arrangements 3a' and 3b'. Fig. 2B Figure 1 shows a design in which the magnet arrangements 3a' and 3b' are fixed on magnet carriers 33a" and 33b" respectively, and the magnet carriers are connected to a stator 3" of the linear motor 1" by an iron-free U-profile section 35". The U-profile section 35" maintains the magnet rows 3a' and 3b' at a constant distance and ensures precise linear guidance for the relative movement of the coil arrangement (the rotor) 5 in the longitudinal direction of the stator 3". Fig. 2C Figure 1 shows another configuration of the linear motor in which the latter function is realized by using two elongated and in longitudinal section U-shaped magnet carriers 33a‴ and 33b‴, which are placed on top of each other with their open sides facing each other and thus form a longitudinally rectangular stator 3‴ of the linear motor 1‴.

[0028] Fig. 3 schematically shows a front view of magnetic track 3. Fig. 1 An exemplary sequence of the polarities of the individual permanent magnets 31. This is a so-called Halbach configuration, in which the magnetization direction of adjacent permanent magnets is tilted relative to each other by 90 degrees in the direction of the longitudinal axis of the magnetic track, and in which, as a result, the magnetic flux is increased on one side of the magnetic track (where the coil arrangement is located in the linear motor), but reduced to almost zero on the other side. Such a special magnetic track configuration does not require an iron return circuit and is advantageously combined with a coil arrangement of the type described below to form an efficient and compact linear motor.

[0029] Fig. 4 Figure 1 shows the conductor paths of three flat coils 51, 53, and 55, which together form a coil group of the coil arrangement of a linear motor according to the invention, with each coil being connected to one of the three phases of a three-phase AC power supply. To distinguish the conductor paths of the individual coils in subsequent illustrations, coil 51 is shown with dashed lines, coil 53 with solid lines, and coil 55 with dashed lines. The open circles indicate connection or twisting points, the function and practical implementation of which are described in more detail below. The conductor paths of the flat coils are each implemented as tracks in one or two conductor planes of a conductive, electrically and magnetically insulating substrate, which is also explained in more detail below.

[0030] As can be seen in the figure, the basic shape of the conductor routing of all three flat coils 51, 53, 55 is essentially rectangular, with one virtual corner of the rectangle being "bridged" by conductor sections inclined relative to both adjacent edges. Each of the flat coils has a small external connection area 51a, 53a, 55a located near one corner of the rectangle.

[0031] According to one aspect of the invention, each of the three flat coils 51, 53, 55 is formed using two conductor layers of a carrier such that all three flat coils are nested inside one another or placed overlapping each other, and yet in the majority of the respective conductor path of each coil, conductor traces are present in both conductor layers, and thus both conductor layers can be used with high efficiency.

[0032] This is in the context of the Fig. 5 and 6 to be understood as follows: Fig. 5 shows the conductor traces of each of the flat coils 51, 53, 55 in the first and second conductor plane of a (not shown) support, and Fig. 6 It shows, in a top-down view, how the three coils are nested inside each other.

[0033] This nesting or overlapping is made possible by the fact that in sections of the conductor paths of each of the three flat coils (hereinafter referred to as "crossing areas"), only one of the two available conductor levels is used, while in the second level, crossing conductors from another of the three coils run. The conductor paths are designed such that a maximum of two of the three coils cross, but never all three. This makes it possible to manage with only two conductor levels despite the presence of three coils. Fig. 5 shows the respective conductor traces 51.1, 51.2 of the flat coil 51 in the first and second conductor plane, the conductor traces 53.1 and 53.2 of the second flat coil in the first and second conductor plane, and the conductor traces 55.1 and 55.2 of the third flat coil in the first and second conductor plane.

[0034] The diagram also schematically illustrates that in some of the conductor sections implemented in only one of the two conductor planes, a widening is provided; see sections 51b, 53b, 53c and 53d, as well as 55b and 55c. This reduces the specific current load of the respective conductor sections and thus the resistance heating in these sections, and the widened conductor sections can even serve as heat sinks for the respective flat coil.

[0035] In the practical implementation of flat coils in two (or more) conductor layers of a multi-layer printed circuit board (PCB), the transitions between the conductor paths in the first and second layers (and possibly further layers) are realized by vertical vias, i.e., by holes that are filled with a conductive material or whose walls are lined with a conductive material, and to which a conductor is brought to connect with the respective other layer (or several other layers; see the following explanations). The technology for implementing vias in multi-layer PCBs is well known to those skilled in the art, as is the structuring of the conductor layers of such PCBs to form conductor paths, so that further explanations can be omitted here.

[0036] Fig. 7 schematically shows a row and stack arrangement of six coil groups 50 arranged side by side. Fig. 6 shown setup, with which overall a design of the coil arrangement or the rotor 5 according to Fig. 1 or 2 This can be realized. Four (each double-sided conductive coated) carrier layers of a multi-layer printed circuit board are shown as examples, each of which incorporates a combined conductor routing as described in Fig. 5 This is shown. Furthermore, the four layers are interconnected via vias in such a way that the respective conductor traces are quadrupled. It should be noted that the number of carrier layers shown here is merely an example; in practice, multi-layer printed circuit boards with up to 20 (or more) conductor layers are used.

[0037] Fig. 8 Figure 5, a schematic longitudinal section of the coil arrangement, shows that each conductor layer is utilized by the nested coils of each coil group and the dense arrangement of the individual coil groups to form the overall coil arrangement with closely adjacent conductor tracks. There are practically no large areas of the individual conductor layers that are not used for the conductor tracks of the flat coils, so that the proposed configuration allows for the realization of an optimally densely packed coil arrangement for a linear motor that can operate at high currents.

[0038] With reference to Fig. 9 , which, in the manner of a top view, shows the multilayer coil arrangement 5 from Fig. 7 As shown in the figure with a magnetic track 3, it is noted that the magnetic track is preferably significantly narrower than the coil arrangement. Specifically, its width is dimensioned such that it covers only the straight, parallel conductor sections of the flat coils of the coil arrangement, but not the sections running obliquely or parallel to the magnetic track, nor the crossing sections. This configuration is chosen to ensure a more uniform force flow and to avoid disruptive inhomogeneities in the magnetic field of the coil arrangement acting on the magnetic track.

[0039] Fig. 10 Figure 1 shows a schematic perspective view of a further embodiment of an electric motor in which the invention can be used, namely a rotary drive 101. This comprises an annular stator 103 made of essentially rod-shaped permanent magnets 131 arranged in a corresponding ring shape and a rotor 5, also annular, with a coil arrangement of the type specified above. As already mentioned in the embodiments explained above, the stator / rotor relationship can also be kinematically reversed. The stator and rotor do not necessarily have to be circular, nor do they have to be annular, but can also have the shape of a circular segment.

[0040] Between the in Fig. 1 bis 2C shown linear motors and the one in Fig. 10In the context of the invention, "intermediate stages" are also possible for the rotary drive shown, i.e., motors with arbitrarily curved, non-closed stators and rotors. It is evident that in non-linear arrangements, both the magnetic elements of the corresponding magnetic arrangements and the coils of the corresponding coil arrangements will have a shape deviating from the rod or rectangular shape mentioned above. The magnetic elements will generally taper towards one end, and the coils will be essentially trapezoidal, or trapezoidal or triangular coils will be inserted into the coil arrangement between essentially rectangular coils with the inventive structure. The above explanations of aspects of the invention and their practical implementation apply largely analogously to the design of such coils.

[0041] Furthermore, the implementation of the invention is not limited to the exemplary embodiments shown in the figures and described above, but also includes numerous modifications and combinations of the individual configurations and features that are within the scope of protection of the annexed claims.

Claims

1. Electric motor, having: - at least one magnetic track (3), which has a plurality of magnetic elements (31) arranged in a longitudinal direction or a ring shape, and - at least one coil arrangement (5), which includes a carrier, which is electrically and magnetically substantially non-conductive with respect to the magnetic track, configured in such a way that the coil arrangement and the magnetic track are able to move in a guided manner relative to one another, and which includes at least one group of three conductive flat coils (51, 53, 55), wherein each of the three flat coils is connected to a phase of a three-phase power supply and wherein the conductor tracks (51.1, 51.2, 53.1, 53.2, 55.1, 55.2) of the three flat coils of the or each group are arranged interleaved or overlapping in a first and second conductor layer of the carrier, which are electrically insulated from each other by an insulating intermediate layer, in such a way that parts of the conductor path of each of the three flat coils are designed one above the other and connected in parallel in the first and second conductor layer and two of the three overlapping flat coils have crossover regions in which the conductor tracks of the first flat coil only run in the first and the conductor tracks of the second flat coil only run in the second conductor layer of the carrier, characterised in that the magnetic track with the magnetic elements and the flat coils of the coil arrangement are dimensioned in coordination with one another such that the crossover regions of the flat coils lie outside the projection of the magnetic elements onto the coil arrangement.

2. Electric motor according to Claim 1, wherein the magnetic track has a plurality of magnetic elements (31) in a Halbach array configuration.

3. Electric motor according to Claim 1 or 2, wherein the magnetic track (3) is associated with a stator and the coil arrangement (5) is associated with a rotor of the electric motor and in particular the stator has substantially the shape of an elongated or annular closed U-profile or rectangle and the rotor is designed to be plate-shaped or strip-shaped so as to match the shape of the stator in such a way that it can move inside the U-profile or rectangle.

4. Electric motor according to one of the preceding claims, wherein the coil arrangement (5) comprises two or more groups of three flat coils (51, 53, 55) respectively connected to a phase of the three-phase power supply, which are arranged consecutively in a longitudinal direction or in a ring shape on or in the carrier.

5. Electric motor according to one of the preceding claims, wherein the carrier is designed as a multi-layer printed circuit board and respectively exactly two adjacent conductor layers of the multi-layer printed circuit board are structured to form the three associated, overlapping flat coils (51, 53, 55), wherein in the crossover regions, the transitions of a flat coil path from the first to the second conductor layer and vice versa are formed by means of vertical vias.

6. Electric motor according to one of the preceding claims, wherein the carrier is designed as a multi-layer printed circuit board with 2m conductor layers (m≥2), in which each of the three associated overlapping flat coils (51, 53, 55) of a group comprises 2 to m substantially identical conductor tracks (51.1, 51.2, 53.1, 53.2, 55.1, 55.2) connected in series, wherein the electrical connections between the conductor tracks connected in series are designed by means of vertical vias through the multi-layer printed circuit board.

7. Electric motor according to Claim 5 or 6, wherein each of the flat coils (51, 53, 55) has a small connection and via region, which is arranged directly on a short side of the respective flat coil and in which vias are placed for connecting the conductor tracks arranged one above the other and connected in series and for the external connection of the flat coil, wherein a dimension of the connection and via region, in particular its length in a longitudinal direction of an elongated flat coil, is less than 10 %, in particular less than 5 %, of the corresponding dimension of the flat coil.

8. Electric motor according to Claim 7, wherein the small connection and via region is respectively positioned near a corner of a polygonal flat coil configuration and comprises a substantially hook-shaped conductor section.

9. Electric motor according to one of Claims 5 to 8, wherein the associated three flat coils (51, 53, 55) formed by structuring the respective two conductor layers of the multi-layer printed circuit board are configured to be substantially rectangular and are arranged interleaved and overlapping in such a way that the long sides of the three flat coils run respectively parallel to one another in the first and second conductor layer, and respectively the largest part of the conductor path of a corresponding side of the two other flat coils is arranged within the rectangle of one of the three flat coils.

10. Electric motor according to one of Claims 5 to 8, wherein the associated three flat coils (51, 53, 55) formed by structuring the respective two conductor layers of the multi-layer printed circuit board are configured to be substantially trapezoidal and are arranged interleaved and overlapping in such a way that the non-parallel sides of the trapezoidal shapes of the three flat coils run respectively parallel to one another in the first and second conductor layer, and respectively the largest part of the conductor path of a corresponding side of the two other flat coils is arranged within the trapezoid of one of the three flat coils.

11. Electric motor according to Claim 9 or 10, wherein all conductors of all three flat coils (51, 53, 55) respectively have the same distance to one another on the long sides of the rectangular conductor configuration or on the non-parallel sides of the trapezoidal conductor configuration and there is no greater distance region within the associated three flat coils.

12. Electric motor according to Claim 11, wherein the distance between the adjacent conductor tracks (51.1, 51.2, 53.1, 53.2, 55.1, 55.2) is smaller than their width, in particular smaller than half their width.

13. Electric motor according to one of Claims 9 to 12, wherein in the substantially rectangular or trapezoidal conductor path of the flat coils (51, 53, 55), respectively one virtual corner of the rectangle or trapezoid is replaced by conductor sections running obliquely to the adjacent sides.

14. Electric motor according to one of the preceding claims, wherein at least part of the conductor paths are widened at least in part of the crossover regions and, due to the current load reduced by the widening, act as heat sinks for the respective flat coil (51, 53, 55).