Improved linear actuator

Abstract

The present invention provides a permanent magnet assembly (300) for a non-commutated linear actuator (100), the permanent magnet assembly (300) comprising: a magnetic core structure (350); and a permanent magnet (400) having a first magnetic pole and a second magnetic pole wherein the magnetic core structure (350) comprises: a central core (360) connected to the first magnetic pole of the permanent magnet; and an outer layer hollow portion (370) connected to a second magnetic pole of the permanent magnet (400); and a gap region (380) between the central core (360) and the outer layer hollow (370), where the magnetic core structure (350) is configured such that magnetic flux generated by the permanent magnet (400) flows between the central core (360) and the outer layer hollow (370) via the gap region (380), and where the magnetic core structure (350) comprises one or more protrusions (361, 371) extending into the gap region (380).

Description

Technical Field

[0001] The present invention relates to a non-commutated linear actuator and more particularly to a permanent magnet assembly for use with such a motor. Background Art

[0002] Linear motors such as non-commutated linear actuators are well known. A non-commutated linear actuator (also known as a voice coil linear actuator, or when a DC signal is applied, a non-commutated DC linear actuator) is a direct-drive linear actuator. It consists of a permanent magnet assembly and a coil assembly, and is configured so that the current flowing through the coil assembly interacts with the permanent magnetic field generated by the permanent magnet assembly to generate a force vector perpendicular to the direction of the current. This force "actuates" the linear actuator, allowing the coil assembly to move in a linear manner along the longitudinal axis.

[0003] Typical non-commutated linear actuators have several disadvantages. First, the interaction between the current flowing in the coil assembly and the permanent magnetic field can produce different forces when the movable member in the actuator is at different positions along the travel length. This requires increased motor control complexity to compensate for these force differences and ensure consistent functionality throughout the linear travel process.

[0004] Furthermore, since these devices rely on the alignment of a movable member that moves linearly relative to a fixed member, alignment between the movable member and the fixed member is critical to achieving the desired force. However, typical non-commutated linear actuators are poorly protected from external forces, such as mechanical shock, resulting in misalignment between the fixed and movable members. Finally, when the coil assembly of a non-commutated linear actuator is part of the movable member in the actuator, there are further issues related to the reliability of the electrical connections to this coil assembly. For example, where wires are used to connect to the coil assembly, regular movement of the movable member may result in rapid wear of the wires, leading to motor failure.

[0005] Additionally, under high load conditions (i.e., large amounts of current are present in the coil assembly), typical non-commutated linear actuators suffer from large amounts of distortion and displacement of the magnetic flux lines within the air gap. This distortion and displacement results in poor motor control linearity, less available force applied to the coils, poor frequency response of the armature, poor repeatability of the armature position, and poor compliance (i.e., how well the armature moves in proportion to the input power without bouncing).

[0006] It would therefore be desirable to provide arrangements for overcoming or at least alleviating the problems of conventional linear actuators. Summary of the invention

[0007] According to a first embodiment of the present invention, a permanent magnet assembly for a non-commutated linear actuator is provided. The permanent magnet assembly comprises: a core structure; and a permanent magnet having a first magnetic pole and a second magnetic pole, wherein the core structure comprises: a central core portion connected to the first magnetic pole of the permanent magnet; an outer hollow portion connected to the second magnetic pole of the permanent magnet; and a gap region located between the central core portion and the outer hollow portion, wherein the core structure is configured so that a magnetic flux generated by the permanent magnet flows between the central core portion and the outer hollow portion via the gap region, and wherein the core structure comprises one or more protrusions extending into the gap region.

[0008] It is understood that the core structure may refer to a mechanical structure having a high magnetic permeability (i.e., the internal dipoles of the structural material are easily oriented in response to an applied magnetic field) to confine and guide the magnetic field. In this case, the core structure is configured to confine and guide the magnetic field generated by the permanent magnet. It is understood that the gap region may refer to one or more air gaps existing between the cylindrical outer hollow portion and the central core portion.

[0009] The terms "central core" and "outer hollow portion" refer to the relative configuration of these features. That is, the outer hollow portion of the magnetic core structure can completely surround the central core and be concentric with the central core. Alternatively, the outer hollow portion may include two arms, one of which covers the top of the central core and the other covers the bottom of the central core. The central core may have a cross-section that is substantially circular, oval, square, rectangular, etc. The outer hollow portion may similarly have a cross-section that is substantially circular, oval, square, rectangular, etc., but lacks material in the center (so that the structure is hollow). However, it is not required that the central core and the outer hollow portion have similar cross-sectional shapes. Nevertheless, in some embodiments, the outer hollow portion and the central core have similar cross-sectional shapes (that is, they may both have a substantially circular cross-section and each have an overall cylindrical shape). For the avoidance of doubt, the "outer hollow portion" may refer to the same features as the "outer pole piece", and the "central core" may refer to the same features as the "inner pole piece".

[0010] It can also be understood that because the outer hollow portion can be concentric with the central core, the two portions can share a center point of the cross-section. It should also be understood that the length of the outer hollow portion (defined by a line along the surface of the outer hollow portion from the proximal end of the permanent magnet assembly to the distal end of the permanent magnet assembly) is substantially parallel to the corresponding length of the central core.

[0011] The terms distal and proximal have been used to define the endpoints of the permanent magnet assembly. It is understood that the central core and the outer hollow portion each extend between respective proximal and distal ends. It is also understood that the end of the permanent magnet assembly where the permanent magnet is located can be considered the proximal end.

[0012] It will also be appreciated that the permanent magnet assembly is designed to define a passage between movable members (also referred to as longitudinally linearly movable members) in a non-commutated linear actuator, and that the passage may include a gap region.

[0013] For completeness, a protrusion may refer to a feature of a magnetic core structure that protrudes or extends from the surface of the magnetic core structure. In this case, one or more protrusions are configured to extend into the gap region, thereby shortening the distance between the outer hollow portion and the central core portion at least at the location of the one or more protrusions.

[0014] It is also understood that the protrusion is a three-dimensional structure. Therefore, it can extend a fixed distance from the entire surface (for example, a trumpet-shaped annular disk extending outward from a cylindrical central core). It is also possible to provide a plurality of discrete, fixed protrusions that do not necessarily extend around the circumference of the central core or the outer hollow portion.

[0015] One advantage of the above configuration is that the one or more protrusions serve to shorten the distance between the outer hollow portion and the central core, thereby enhancing the magnetic field present in the air gap, compared to an equivalent configuration in which the protrusions are not present. This is advantageous because a higher magnetic field density (i.e., magnetic flux) in the gap region means that more force can be transmitted to the conductive element (e.g., a wound coil in a non-commutated linear actuator) present in the gap region. This effect is achieved without increasing the strength and size of the permanent magnets, further improving the cost-effectiveness and size of such permanent magnet assemblies.

[0016] Another advantage is that these protrusions reduce the distortion of the flux lines in the air gap that can exist when high currents are carried on the coil. Less distortion and displacement of the flux lines in the air gap is advantageous because it improves control linearity (and therefore improves the relationship between input power and armature position).

[0017] Furthermore, by reducing the amount of twist and displacement of the flux lines, more force is available to be applied to the coils because the flux density passing through the coils in a direction perpendicular to the current in the coils is higher. This also ensures improved frequency response of the armature and better repeatability of the armature position.

[0018] Finally, reducing the amount of twist and displacement of the magnetic flux lines within the air gap results in better compliance of the linear actuator (i.e., the degree to which the armature moves accurately in proportion to the input power without bouncing).

[0019] In some embodiments, the one or more protrusions of the magnetic core structure include one or more core protrusions extending radially outward from the central core into the gap region.

[0020] In some embodiments, the one or more protrusions of the magnetic core structure include one or more hollow portion protrusions extending radially inward from the outer hollow portion into the gap region.

[0021] It is understood that the one or more core protrusions are features that are integrated with or attached to the central core. It is also understood that the one or more hollow protrusions are integrated with or attached to the outer hollow.

[0022] One benefit of having protrusions on only one of the central core or the outer hollow portions is that the same benefit of increased magnetic flux can be achieved while limiting the increase in cost and manufacturing complexity. For example, as opposed to providing protrusions on both the central core and the outer hollow portions (each requiring a different process), the protrusions can be implemented only on the outer hollow portion, thereby allowing a more simplified design for the central core (or vice versa).

[0023] In some embodiments, at least one of the one or more core protrusions corresponds to and is aligned with a corresponding hollow portion protrusion of the one or more hollow portion protrusions.

[0024] It is understood that when a core protrusion "corresponds to and is aligned with" a corresponding hollow protrusion, this refers to a configuration in which the core protrusion is located at a specific position along the length of the central core, and the corresponding hollow protrusion is also located at the same position along the length of the outer hollow. In other words, this can be understood as the two protrusions extending toward each other, thereby further reducing the distance between the central core and the outer hollow compared to a single protrusion of the same size.

[0025] This configuration is particularly advantageous when it is desirable to optimize the magnetic flux present in the air gap while also keeping the length of each protrusion to a minimum. In other words, having an equally shortened air gap (with corresponding protrusions on either side) means that each of the respective protrusions forming the air gap is smaller than a corresponding configuration having a single, longer protrusion (extending from either the central core or the outer hollow portion). This makes the permanent magnet assembly robust (since the shorter protrusions are less likely to break) and significantly improves the magnetic flux density compared to a configuration without protrusions.

[0026] In some embodiments, the central core has a substantially circular, substantially oval, or substantially square axial cross-section.

[0027] In some embodiments, the outer hollow portion has a substantially circular, substantially oval, or substantially square axial cross-section, and wherein the outer hollow portion includes at least one elongated slot along its length to allow access to the interstitial region.

[0028] It will be appreciated that the at least one elongated slot is a slit that completely protrudes through the thickness of the outer layer hollow portion. Such an elongated slot is designed to allow electronic commutation of components that may be present in the gap region. This allows power to be delivered to, for example, a wound coil present in the gap region to form a non-commutated linear actuator.

[0029] As mentioned above, the central core and the outer hollow portion may each take on different shapes, which are ultimately determined by the shape of the linear actuator of which the permanent magnet assembly is a part. For example, where the movable member of the linear actuator is a hollow cylinder, it may be advantageous to provide both the central core and the outer hollow portion with a substantially circular axial cross-section to provide an annular gap region in which the movable member is located.

[0030] One advantage of designing the permanent magnet assembly in this manner (i.e., having elongated slots in the outer hollow portion) is that the magnetic flux generated between the outer hollow portion and the central core is maximized because the magnetic flux is transmitted along the length of the permanent magnet assembly except for the elongated slot portions.

[0031] In some embodiments, the one or more core protrusions have a substantially circular, substantially oval, or substantially square axial cross-section.

[0032] In some embodiments, the one or more hollow portion protrusions have a substantially circular, substantially oval, or substantially square axial cross-section, and wherein the hollow portion protrusion comprises at least one elongated slot along its length to allow access to the gap region.

[0033] As mentioned above, the protrusion is a three-dimensional structure. Therefore, it can extend a fixed distance from the entire surface (for example, a trumpet-shaped annular disk extending outward from a cylindrical central core). The above configuration defines that the protrusion can have a substantially circular, oval or square cross-section. This can refer to the cross-section defined by the outermost edge or the innermost edge of the protrusion. For example, when in the case of a cylindrical central core, and the annular disk extends outward from a point along the length of the central core, the annular disk protrusion can be considered to have a substantially circular cross-section. This is because the outermost edge of the annular disk is circular.

[0034] In this case, the axial cross-section of a protrusion may refer to the cross-section of the protrusion and the central core itself. For example, a protrusion of fixed length extending from a cylindrical central core may be considered to have a circular cross-section.

[0035] Alternatively, the axial cross-section of the protrusion may be a cross-section of the protrusion alone (in the absence of a central core). In this way, the cross-section of such a core protrusion may also be considered to be annular (rather than circular).

[0036] It can be understood that the elongated slots of the hollow portion protrusions are aligned with the corresponding elongated slots of the outer hollow portion. This is because the elongated slots of the outer hollow portion lack magnetically permeable material and therefore nothing can protrude from this feature.

[0037] In some embodiments, the one or more core protrusions include a plurality of core protrusions, and / or the one or more hollow portion protrusions include a plurality of hollow portion protrusions.

[0038] One advantage of multiple core protrusions and / or hollow protrusions is that the regions of increased magnetic flux can be distributed over the length of the permanent magnet assembly. For example, where a first core protrusion is present at a first location along the length of the core structure, and where a second core protrusion is present at a second location along the length of the core structure (the second location being distal or proximal to the first location), this provides at least two different regions of increased magnetic flux within the gap region. The distribution of these protrusions (and therefore the regions of increased magnetic flux) improves the operation of a non-commutated linear actuator implementing such a permanent magnet assembly. This is because the movable member in the linear actuator will experience a more uniform magnetic flux over the length that the movable member may travel.

[0039] In some embodiments, each of the plurality of core protrusions is spaced apart from an adjacent core protrusion by a second distance, and each of the plurality of hollow portion protrusions is spaced apart from an adjacent hollow portion protrusion by a second distance.

[0040] It is advantageous to have each core protrusion spaced a fixed distance from each other. The same is true for the hollow portion protrusions. This is because the fixed distance further ensures that the movable member of the non-commutating linear actuator experiences uniform forces acting thereon over the length that the movable member may travel.

[0041] In some embodiments, the length of the second distance may be shorter than the length of the associated movable member of the non-commutated linear actuator. When this is the case, there is no position along the travel length of the movable member where the movable member will not be present in the region of increased magnetic flux (formed by the aforementioned protrusion).

[0042] In some embodiments, the permanent magnet assembly further includes a filler material positioned to cover sides of the one or more protrusions.

[0043] It is understood that the "side" of a protrusion refers to an edge or region facing in a substantially proximal or distal direction (i.e., facing the proximal direction or distal direction of the core structure). When multiple protrusions are present on the same portion of the core structure (e.g., the central core), the "sides" of two protrusions are the portions that each faces each other. In other words, the side is the portion of each protrusion that does not form the base of the protrusion or does not face the associated gap region.

[0044] "Covering" may refer to a feature that completely covers the sides of a protrusion. Alternatively, it may only cover a selected portion of the sides of a protrusion.

[0045] An advantage of introducing material to cover the sides of the protrusion is that the protrusion is prevented from having sharp edges. Sharp edges are undesirable, especially when the movable member travels in the gap area. By providing the filler material, any sharp corners associated with the protrusion can be rounded. Therefore, if a non-commutated linear actuator having such permanent magnets is subjected to any external forces (such as being dropped, or the chassis of the linear actuator being hit), the movable member of the linear actuator will not hit the sharp corners during its movement. In other words, the permanent magnet assembly of this embodiment provides all the advantages associated with increased magnetic flux at a specific point along the core structure, but it does not degrade the structural restoring force of the associated linear actuator.

[0046] In some embodiments, the filling material is configured to completely fill spaces between adjacent core protrusions of the plurality of core protrusions, and the filling material is configured to completely fill spaces between adjacent hollow portion protrusions of the plurality of hollow portion protrusions.

[0047] It will be understood that "adjacent" refers to two protrusions that are close to each other without an intermediate protrusion. Therefore, each side of the adjacent protrusions is completely covered when the filler material completely fills the space between them. In addition, completely filling the space between the protrusions means that the channel traveled by the movable member of the linear actuator is uniform over the entire length of the permanent magnet assembly. In this way, the channel is defined only by the gap between the axial section of the core protrusion (if not present, the surface of the central core) and the axial section of the hollow protrusion (if not present, the surface of the outer hollow).

[0048] The benefit of having a uniform profile of the channel / gap area is that it can improve structural integrity. In addition, as mentioned above, any simplification of the edges along the length of the permanent magnet assembly is beneficial for impact resistance because the movable member will not be easily damaged when in contact with a flat surface. This also helps to bring the movable member back into alignment because the uniform channel formed by the filler material can limit the allowable movement of the movable member, thereby preventing it from getting stuck.

[0049] In some embodiments, the filler material includes a resin.

[0050] The filling material may be any material which is relatively non-magnetic relative to the magnetic permeability of the central core, the outer hollow portion and the associated protrusions. This means that the filling material has a negligible effect on the magnetic field provided in and guided through the magnetic core structure. It is also advantageous to provide a material with a low friction coefficient so as not to negatively affect movable components present in a channel at least partially formed by the filling material.

[0051] According to the present invention, a non-commutated linear actuator is also provided, which has a fixed component and a movable component, the movable component is configured to move relative to the fixed component in a longitudinal direction, wherein the fixed component includes a permanent magnet assembly according to any one of the above-mentioned embodiments, and wherein the movable component is located in an air gap area of ​​the permanent magnet assembly.

[0052] It is also understood that a non-commutated linear actuator is also referred to as a voice coil linear actuator (or when a DC signal is applied, a non-commutated DC linear actuator) and is a direct-drive linear actuator that is composed of a permanent magnet assembly and a movable member and is configured to interact with a permanent magnetic field generated by the permanent magnet assembly to generate a force vector perpendicular to the direction of the current.

[0053] It can be understood that the movable member is also referred to as a longitudinally linearly movable member herein.

[0054] In some embodiments, the movable member includes at least one electrically conductive winding.

[0055] It will be appreciated that the movable member is provided with an electrically conductive winding so that current can be driven along the path of the winding so that the current flowing through the coil assembly interacts with the permanent magnet assembly.

[0056] In some embodiments, the movable member comprises a structure comprising at least one of the following materials: carbon fiber, thermoplastic plastic, thermoset plastic, or synthetic fiber material, and wherein the at least one conductive winding is wound around the structure.

[0057] The tube can be formed from many insulating materials, including, for example, carbon fiber, polyetheretherketone, polyetherketoneketone, or any other type of insulating polymer. It can also be formed from synthetic fiber materials, such as Kevlar.

[0058] Wrapping the at least one electrically conductive winding around the structure may increase the current density around the circumference of the structure, which results in a strong interaction between the input current and the magnetic flux generated by the permanent magnet assembly.

[0059] In some embodiments, the structure is tubular to fit within a cylindrical linear actuator. However, the structure may take any suitable shape (eg, a hollow rectangular prism) to fit the contour of a particular linear actuator.

[0060] In some embodiments, the non-commutated linear actuator further comprises an electrical interface configured to connect the at least one electrically conductive winding to a power source via the at least one elongated slot.

[0061] The electrical junction of the present invention may be any connection (eg a direct wired connection) to the at least one electrically conductive winding.

[0062] In some embodiments, the electrical interface includes at least one flexible conductive ribbon configured to transfer power from a power source to the at least one conductive winding located on the movable member.

[0063] "Flexible conductive tape" may refer to a strip of material or a ring of material. The conductive tape itself may be at least partially formed of a conductive material, or there may be conductive elements located on, around, or connected to a non-conductive substrate of the conductive tape. It is also understood that "flexibility" refers to the ability of the conductive tape to bend or deform without breaking.

[0064] In some embodiments, the flexible conductive tape is an elastic element that can be deformed (e.g., compressed) from a static state to an assembled state when placed between a first conductive surface and a second conductive surface. The flexible conductive tape in this assembled state can withstand mechanical strain, thereby forcing the flexible conductive tape to return to its static state. Such a property can allow for improved electrical connection between the first conductive portion and the second conductive portion because the surface area of ​​the electrical contact is maximized.

[0065] In some embodiments, the at least one flexible conductive strip is configured to mechanically interact with the first contact region and mechanically interact with the second contact region. Here, the first region may be a conductive strip on the movable member, and the second region may be a conductive strip connected to a chassis of the non-commutated linear actuator. Thus, when the second portion moves relative to the first portion, the flexible conductive strip is configured to travel along a predetermined path and maintain electrical connection between the first contact region and the second contact region.

[0066] In some embodiments, to travel along the predetermined path, the at least one flexible conductive strip is configured to move in a rolling motion as the movable member of the linear actuator moves linearly.

[0067] In such embodiments, the at least one flexible conductive strip is configured to transmit power to the at least one conductive winding on the longitudinally linearly movable member or the movable member.

[0068] Such a configuration can replace the wired connection with the conductive winding on the longitudinally linearly movable member or the movable member. These wires are subjected to great stress during the repeated process of the linear motor being driven. Therefore, the linear electric motor of the present invention is advantageous in reducing the wear of the components and can increase the life of the motor itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Advantageous embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0070] Figure 1A and Figure 1B is an exemplary linear actuator having a smooth surface with a permanent magnet assembly.

[0071] Figure 2 is an isometric view of a cylindrical linear actuator according to one embodiment of the present invention.

[0072] Figure 3 1 is an exploded perspective view of the cylindrical linear actuator shown in FIG. 1 .

[0073] Figure 4 1 is a cross-sectional view of a cylindrical linear actuator.

[0074] Figure 5 is a two-dimensional cross-sectional view of a permanent magnet assembly according to one embodiment of the present invention, and illustrates the magnetic flux existing in the permanent magnet assembly.

[0075] Fig. 6A and Figure 6B is a three-dimensional view of an outer hollow portion for use with a permanent magnet assembly according to one embodiment of the present invention.

[0076] Figure 7 is a three-dimensional view of a permanent magnet assembly according to one embodiment of the present invention, wherein the permanent magnet assembly is installed in a linear actuator.

[0077] Figure 8 is an isometric view of a rectangular linear actuator according to one embodiment of the present invention.

[0078] Fig. 9 and Fig. 9A show Figure 8 A cross-sectional view of a rectangular linear actuator and a partial cross-sectional view of the magnetic flux lines shown.

[0079] Fig.10 is a diagram of an exemplary flexible conductive tape for use in a linear actuator according to one embodiment of the present invention.

[0080] Fig.11 Yes Figure 7Another illustration of a flexible conductive tape is shown. DETAILED DESCRIPTION

[0081] In the following description, the terms "first", "second", "primary" and "secondary" are not intended to be limiting, but are used to distinguish different elements from each other. The longitudinal axis of the linear actuator can be considered as an axis extending in the direction between the proximal end (i.e., the power input side) and the distal end of the electric motor. In other words, this longitudinal axis follows the direction of travel of the motor.

[0082] Figure 1A and Figure 1B Phenomena are described with respect to a cylindrical linear actuator having a certain length, the cylindrical linear actuator including a permanent magnet assembly having an inner pole piece and an outer pole piece. Figure 1A It can be seen that the magnetic flux lines (dashed lines) emerge from the permanent magnet and pass through the outer pole piece of the permanent magnet assembly, across the air gap, into the inner pole piece of the permanent magnet assembly, and close the magnetic circuit at the other end of the permanent magnet. In this case, the surfaces of both the outer pole piece and the inner pole piece in the air gap region are smooth and have no protruding features protruding into the air gap. The magnetic field present through the air gap is configured to interact with the current flowing in the coil layer (which exists within the air gap) to produce a linear force on the coil layer.

[0083] Figure 1B describe Figure 1A Magnetic flux lines of a linear actuator under high load conditions (i.e., when a large amount of current is passed through the coils of the coil layer). In this condition, the magnetic flux lines (also shown in dashed lines) become distorted and displaced within the air gap where they intersect the coils of the coil layer. In the depicted example, the magnetic flux lines are displaced backwards, however, it will be appreciated that if the polarity of the current in the coil is reversed, the magnetic flux lines will be displaced forwards.

[0084] This phenomenon is equivalent to the linear actuator for armature reaction in a DC rotary machine with permanent magnets or electromagnets to generate field flux. That is, in a rotary machine, the geometric magnetic neutral axis (GMNA) is subjected to a secondary magnetic field generated by the armature (armature flux), and these two magnetic fields interact (which is determined by the electrical neutral axis ENA) so that a rotational torque is generated when the angle between them is 90 degrees or less.

[0085] As mentioned above, Figure 1A and Figure 1B The actuator has a permanent magnet assembly wherein the inner and outer pole pieces are substantially smooth along their surfaces in the air gap region.

[0086] therefore, Figure 1A and Figure 1BThe actuator shown has significant problems associated with motor control. Specifically, the distorted flux lines within the air gap are disadvantageous because they result in poor control linearity, less available force applied to the coil, poor frequency response of the armature, poor repeatability of the armature position, and poor compliance (i.e., how well the armature moves in proportion to the input power without bouncing).

[0087] The first embodiment of the cylindrical linear actuator 100 is as follows Figures 2 to 4 shown. Figure 2 An isometric view of the assembled linear actuator 100 is shown, and Figure 3 An exploded perspective view showing the linear actuator 100; and Figure 4 A cross-sectional view of the linear actuator 100 is shown to provide further detail regarding the internal components.

[0088] The cylindrical linear actuator 100 includes: a fixed member 105; and a movable member 110. In operation, power (e.g., current) is transmitted from the fixed member 105 to the movable member 110. In the illustrated embodiment, the current flows around the surface of the movable member 110 and interacts with the permanent magnet field present in the linear actuator 100 to generate a force vector. As such, the linear actuator can be considered a type of non-commutated linear actuator (also colloquially referred to as a "voice coil" motor).

[0089] Such a linear actuator can be operated bidirectionally by adjusting the polarity of the input voltage / current applied to the input terminals of the linear actuator.

[0090] Since such a linear actuator 100 requires current to be present on the movable member 110, there is a mechanism for transmitting the input voltage / current from the input terminals of the linear actuator 100 to the movable member 110. This may be achieved with any number of engagement elements as will be appreciated by the skilled person.

[0091] In one embodiment of the present invention, the electrical interface of the linear actuator 100 (i.e., the electrical interface between the fixed member and the movable member) is provided by one or more flexible conductive strips 150. The one or more flexible conductive strips 150 are configured to transmit current from the fixed power rails 107a, 107b (power rails fixed to the fixed member 105 of the linear actuator 100) to the movable power rails 112a, 112b (power rails fixedly mounted on the movable member 110 of the linear actuator 100).

[0092] In some cases, there is a first electrical junction formed by a first set of flexible conductive strips, a first fixed power rail 107a, and a first movable power rail 112a. The first set of flexible conductive strips is configured to transmit a first electrical signal between the first fixed power rail 107a and the first movable power rail 112a. There may be multiple flexible conductive strips 150 to ensure that appropriate power can be transmitted to the movable member 110 and to ensure that the current is uniformly transmitted to the movable member 110 along the length of the movable member 110.

[0093] In some cases, there is a second electrical junction formed by the second set of flexible conductive strips, the second fixed power rail 107b, and the second movable power rail 112b. The second set of flexible conductive strips 150 is configured to transmit a second electrical signal between the second fixed power rail 107b and the second movable power rail 112b. There may also be multiple flexible conductive strips 150 to ensure that appropriate power can be delivered to the movable member 110 and that the current is evenly delivered to the movable member 110 along the length of the movable member 110.

[0094] In this case, the first electrical joint and the second electrical joint are provided to transmit the bipolar electrical signal to the movable member 110. That is, the second electrical joint serves as a return path for the signal transmitted through the first electrical joint. In other words, when a power source is connected to the two input terminals of the linear actuator 100, current flows from the power source through the first electrical joint, around the surface of the movable member 110, and flows out of the second electrical joint to return to the power source.

[0095] In some embodiments, at least one conductive winding (not shown) is provided on the movable member 110, which can be wound around the structure of the movable member 110. The action of winding the conductive winding around the movable member 110 represents that more force can be generated by the linear actuator without increasing the voltage of the power supply. As described above, the current flowing through the coil assembly interacts with the permanent magnetic field generated by the permanent magnet assembly to generate a force vector perpendicular to the direction of the current.

[0096] Additional loops of the conductive windings increase the current density around the movable member 110, thereby increasing the force experienced by the linear actuator 100 due to interaction with the permanent magnetic field. However, the linear actuator 100 may also operate if the current flows around the surface of the movable member 110 without multiple loops.

[0097] like Figure 3As shown, the first electrical joint and the second electrical joint may be located on opposite sides of the linear actuator 100. However, other configurations are possible (including, for example, the first electrical joint and the second electrical joint being adjacent on the same side of the linear actuator 100).

[0098] The one or more flexible conductive strips 150 provide a low friction electronic engagement between the fixed member 105 and the movable member 110 in the linear actuator 100. When the movable member 110 moves linearly along the longitudinal axis, the one or more flexible conductive strips 150 are configured to move in a rolling manner in the same direction as the movable member 110. This type of joint provides a lower friction joint than a relatively static joint and is less prone to wear than electrical joints using brushes or direct wiring arrangements.

[0099] Thus, the electrical joint may be considered an improved electronic commutation assembly that provides high current capacity, high wear resistance, and low friction, all of which properties make the electrical joint particularly useful for transmitting electrical signals to an electric motor assembly.

[0100] As described above, the cylindrical linear actuator 100 according to one embodiment of the present invention includes the permanent magnet assembly 300 for generating a constant permanent magnetic field.

[0101] The permanent magnetic field is generated by a permanent magnet assembly 300 located within the chassis 106 of the fixed member 105. For the avoidance of doubt, Figure 2 and Figure 3 The permanent magnet assembly 300 is not shown, but can be seen in Figure 4 in the cross-sectional view.

[0102] Reference Figure 4 and Figure 5 The permanent magnet assembly 300 includes: a permanent magnet 400 having a first magnetic pole (eg, a north pole) and a second magnetic pole (eg, a south pole); and a magnetic core structure 350 .

[0103] In some embodiments, the magnetic core structure 350 is made of a material with high magnetic permeability to confine and guide the permanent magnetic field generated by the permanent magnet 400. In some embodiments, the magnetic core structure 350 may include: ferromagnetic materials, such as iron, other ferromagnetic compounds; or silicon. The magnetic core structure 350 may or may not be laminated.

[0104] The magnetic core structure 350 includes two parts: a central core part 360 and an outer hollow part 370. Figure 4 In the illustrated cylindrical embodiment of the linear actuator 100 , the outer hollow portion 370 has a generally annular cross-section, while the central core 360 ​​has a generally circular cross-section.

[0105] The cross-section of the outer hollow portion 370 may have at least one elongated slot 375 along a portion of the length of the permanent magnet assembly 300 to accommodate an electrical interface.

[0106] Best as Figure 2 As shown in the embodiment of FIG. 3 , there may be two elongated slots 375 aligned with the two electrical joints. Thus, Figure 2 The cross-section of the outer hollow portion 370 in the embodiment of the present invention is generally annular, wherein material on a first side of the ring and on an opposite second side of the ring is removed. The removal of material forms an elongated slot 375 in the outer hollow portion 370, which allows power to be delivered to the movable member 110 generally located within the outer hollow portion 370.

[0107] The central core portion 360 is connected to a first magnetic pole of the permanent magnet 400 , while the outer hollow portion 370 is connected to a second magnetic pole of the permanent magnet 400 .

[0108] Best as Figure 5 As shown, the central core 360 ​​and the outer hollow portion 370 are separated by a gap region 380. The gap region 380 has a sufficient width so that when the permanent magnet assembly 300 is installed in the linear actuator 100, at least a portion of the movable member 110 of the linear actuator 100 can be placed in the gap region 380.

[0109] In other words, it should be appreciated that the gap region 380 defines a channel along the length of the permanent magnet assembly 300 (and therefore along the length of the associated linear actuator), and that the movable member 110 is configured to move within this channel.

[0110] like Figure 5 As shown, the magnetic field travels from the north pole of the permanent magnet 400 to the south pole of the permanent magnet 400 through the core structure 350. The magnetic field travels between the central core portion 360 and the outer hollow portion 370 through the gap region 380.

[0111] Due to these protrusions, there may be some minimal local deformation of the magnetic flux lines in response to high current conditions in the coil, but displacement of the magnetic flux lines along the length of the outer hollow portion 370 and the central core 360 ​​is substantially avoided (e.g., at Figure 1A and Figure 1B displacement seen).

[0112] In other cases, the permanent magnets 400 may be connected in the opposite direction (i.e., the north pole is connected to the outer hollow portion 370 and the south pole is connected to the central core 360). Although the opposite polarity of the power supply is necessary to provide equivalent control, this configuration does not affect the operation of the linear actuator 100. This is because applying the same voltage to the linear actuator 100 will cause the movable member 110 to move distally or proximally depending on the orientation of the magnets.

[0113] The permanent magnet 400 can be any of the following types: aluminum nickel cobalt (AlNiCo), ferrite, samarium cobalt (SmCo), flexible rubber, or neodymium magnets, also known as neodymium iron boron magnets (NdFeB). In some embodiments, the permanent magnet is a neodymium iron boron magnet (NdFeB) permanent magnet that can have axial magnetization.

[0114] In some embodiments, the permanent magnet may be cylindrical with a width of about 5 to 40 mm (preferably 15 mm) and a diameter of about 20 to 40 mm (preferably 31.5 mm).

[0115] In some embodiments, the magnetic flux density at the surface of the permanent magnet 400 is about 0.1 to 2 Tesla (preferably 1.7 Tesla).

[0116] In such Figure 4 In the illustrated embodiment, the movable member 110 has the shape of a hollow tube, surrounding a central core 360 ​​(which is generally cylindrical), and surrounded by an outer hollow portion 370 (which is generally in the shape of a hollow cylindrical tube).

[0117] To further improve the performance of the linear actuator 100, the core structure 350 may include one or more protrusions 361, 371 extending into the gap region 380. These protrusions 361, 371 are used to shorten the distance between the central core portion 360 and the outer hollow portion 370, thereby increasing the magnetic flux density in the air gap.

[0118] In such Figure 4 and Figure 5 In the illustrated embodiment, there are a plurality of protrusions 361 along the length of the central core 360 ​​, and a corresponding plurality of protrusions 371 along the length of the outer hollow portion 370 .

[0119] like Figure 5 As shown, the majority of the magnetic flux in the gap region 380 exists between the corresponding tooth-like protrusions 361, 371. In this embodiment, such protrusions 361, 371 provide regions of increased magnetic flux at regular intervals along the length of the permanent magnet assembly 300.

[0120] exist Figure 4In the cylindrical linear actuator 100, it can be seen that each protrusion 361 extends around the circumference of the central core 360. In other words, each protrusion 361 extending from the central core 360 ​​(i.e., the core protrusion) has a generally annular cross-section (or, the cross-section of the protrusion and the central core 360 ​​below is circular). Each corresponding protrusion 371 extending from the outer hollow portion 370 (i.e., the hollow portion protrusion) also has a generally annular cross-section. For further details, Fig. 6A and Figure 6B One embodiment of an outer hollow portion 370 is shown.

[0121] exist Figure 4 In the embodiment of the present invention, there is a cavity between each adjacent core protrusion 361, and there is a similar cavity between each adjacent hollow protrusion 371. These cavities can be seen in Figure 5 In the cross section shown.

[0122] In some embodiments, the width of the tooth-like protrusions can be about 1 to 10 mm (preferably 2 mm). Figure 4 As shown, each of these cavities is filled with a filling material 365, which may be a resin. Figure 4 In the embodiment of the present invention, the cavity is completely filled so that the gap region has a uniform width over the entire length of the permanent magnet assembly (and so that the channel of the movable member of the associated linear actuator does not have any corners).

[0123] As described above, it is beneficial for the channel / gap region 380 to have a uniform profile in order to prevent sharp edges of the movable member 110 that may interfere with the linear actuator 100. This is particularly beneficial for improving impact resistance, as the movable member 110 is not easily damaged when in contact with a flat surface, and it also helps the movable member 110 return to alignment, as the uniform channel formed by the filler material 365 can limit the allowable movement of the movable member 110, thereby preventing it from getting stuck.

[0124] like Figures 2 to 4 as well as Figure 7 It can be seen that, in some embodiments, a guide rail 115 is installed on the inner surface of the movable member 110. In some embodiments, there may be a plurality of guide rails 115, for example, one guide rail on each side of the movable member 110.

[0125] exist Figures 2 to 4In the embodiment of the present invention, there is a first rail 115a mounted on one side of the interior of the movable member 110, and a second rail 115b mounted on the opposite side of the interior of the movable member 110. In this embodiment, the rails 115 are aligned with the elongated slots 375 of the outer hollow portion 370 (to minimize magnetic flux loss along the length of the movable member 110), although this is not absolutely necessary. When the rails 115 are present, the central core 360 ​​has one or more cutouts to accommodate the rails 115.

[0126] The purpose of the guide rail 115 is to improve the sliding dynamics of the linear actuator 100. In some embodiments, the guide rail 115 may slide over the ball bearings or rollers 390. Such rollers 390 are Figure 4 It is shown in that it can be made of a low friction material such as polyetheretherketone. Figure 7 Yes Figures 2 to 4 An alternative isometric view of a cylindrical linear actuator 100 is shown. In this view, the electrical interfaces are hidden and the view is rotated to emphasize the guide rails 115 on the inside of the movable member 110 and the corresponding cutouts in the central core 360 ​​of the permanent magnet assembly 300.

[0127] Figure 8 1 is an isometric view of a rectangular linear actuator 120 according to another embodiment of the present invention. The rectangular linear actuator 120 includes: a fixed member 125; a movable member 130; and a permanent magnet assembly 310. The rectangular linear actuator 120 operates in substantially the same manner as the cylindrical linear actuator 100, except for the shape of the movable member 130 and the shape of the permanent magnet assembly 310 (which is similar to the permanent magnet assembly 300). That is, the rectangular linear actuator 120 relies on the same principles as the interaction between the current flowing on the movable member 110 and the permanent magnetic field, and the above principles will also apply to the rectangular embodiment.

[0128] like Figure 8 As shown, the movable member 130 of the rectangular linear actuator 120 has the shape of a hollow rectangular prism. As shown in the embodiment, the top surface of the hollow rectangular prism is located in a first channel, and the first channel is formed as a gap between the central core 360 ​​of the permanent magnet assembly 310 and the first arm of the outer hollow portion 370. The bottom surface of the hollow rectangular prism is located in a second channel, and the second channel is formed as a gap between the central core 360 ​​of the permanent magnet assembly 310 and the second arm of the outer hollow portion 370. In this way, any current flowing on the top surface or the bottom surface of the movable member 130 is configured to interact with the permanent magnetic field present in the channel (i.e., the gap area formed by the permanent magnet assembly 310). In other words, a conductive path exists on at least one surface of the rectangular prism. This conductive path can be formed by at least one conductive winding wound on the surface of the movable member 130. Although Figure 8 Although not shown, the rectangular linear actuator 120 may also have one or more electrical joints for delivering current to the movable member 130, and these electrical joints may include one or more flexible conductive strips 150 (which are the same as the flexible conductive strips 150 in the cylindrical linear actuator 100). The electrical joint between the fixed member 125 and the movable member 130 may be the same as the electrical joint of the cylindrical linear actuator 100.

[0129] In operation, power (e.g., current) is delivered from the fixed member 125 to the movable member 130. Similar to the cylindrical case, there is a permanent magnet assembly that provides a magnetic field within the gap region 385 to interact with the current on the movable member 130. Figure 8 In the illustrated embodiment, the permanent magnet assembly 310 of the rectangular linear actuator 120 includes a plurality of protrusions 362, 372, both of which are located on the central core 360 ​​(core protrusions 362) and on the outer hollow portion 370 (hollow portion protrusions 372). It is also contemplated that the protrusions 362, 372 may be present on only one of the central core 360 ​​or the outer hollow portion 370. These protrusions serve the same purpose as the protrusions of the cylindrical linear actuator 100, and thus the principles described above also apply thereto. In a particular embodiment, the cavities or spaces between adjacent protrusions 362, 372 on the central core 360 ​​and the outer hollow portion 370 are at least partially filled with a filling material 365 (e.g., a resin). The filling material 365 may be the same filler as the embodiment of the cylindrical linear actuator 100. In the example shown in FIG. Figure 8 In the illustrated embodiment, the spaces between adjacent protrusions are completely filled to create a smooth path for the movable member 130. Figure 8 As shown, the filler material eliminates the sharp corners of the protrusions and provides a smooth channel for the movable member 130 to travel therein. If the linear actuator 120 is subjected to any external force (such as being dropped, or the chassis of the linear actuator being hit), the movable member 130 of the linear actuator will not hit the sharp corners during its movement, thereby improving the stability of the linear actuator 120. In more detail, the cross-section of the linear actuator 120 is shown in Fig. 9 , and a partial cross-sectional view (showing magnetic flux lines through the movable member 130 and the fixed member 125) is shown in Fig. 9A middle. Fig.10 and Fig.111 is an exemplary flexible conductive ribbon 150 for use in a linear actuator according to an embodiment of the present invention. As shown in these figures, the flexible conductive ribbon 150 can include a plurality of notches 170 that can be dispersed at at least one edge of the flexible conductive ribbon 150. In some cases, there can be a first plurality of notches 170 along a first edge of the flexible conductive ribbon 150 and a second plurality of notches 170 along a second edge of the flexible conductive ribbon 150. In some cases, the linear actuator can include features that interact with the notches of the flexible conductive ribbon to ensure that adjacent flexible conductive ribbons do not come into contact and to improve rolling motion of the flexible conductive ribbon between power rails of the electrical joint. However, this feature is not required.

[0130] These flexible conductive strips 150 can be flexible metal foils, such as stainless steel, with a coating on at least one side. In some examples, this coating can be titanium nitride (which can be applied, for example, by vacuum deposition or sputtering). This coating allows very low friction, further enhancing long term operation of the conductive strips and rails. Alternatively, a high performance polymer film material (such as KAPTON®) can be used. TM , which is a polyimide plastic film, and PET or polyethylene terephthalate) to replace metal foil. This polymer film can have excellent flexibility and can withstand multiple flexing and bending cycles without failure. This polyimide film can also be coated with a variety of highly conductive coatings and finishes, such as graphene. Then, further coatings can be applied by ion deposition in solution through chemical plating or electroplating. This allows the use of metals in solution, such as cupric chloride, copper sulfate, nickel, palladium, ruthenium or any other suitable metal. The process of adding multiple layers of plating and coatings to a flexible plastic substrate is very suitable for mass-produced small motors and can further reduce the current dependence of such motors on the precious metals used. The coating can also be applied to the polymer film using liquid nanosilver ink. This ink can be delivered by inkjet, or deposited by screen printing or rotogravure printing process, and involves a photocurable nano silver oxide ink that immediately (via surface reduction) becomes metallic when in contact with a polymer such as PET (polyethylene terephthalate). This conversion from oxide to metal (by water-assisted electron transfer) can be used to promote further deposition of chemical copper (on top of the cured nano silver coating), thereby achieving a very low cost flexible conductive tape or conductive disk for the present invention.

[0131] The above description is made with reference to the embodiments currently disclosed by the present invention. Those skilled in the art may make modifications and changes to the described structures without meaningfully departing from the principles, spirit and scope of the present invention. As will be appreciated by those skilled in the art, the drawings are not necessarily drawn to scale, and any feature or combination of features described in any one embodiment may be incorporated into any other embodiment or in combination with any other features of other embodiments as desired or required. Therefore, the above description should not be understood as relating only to the precise structures described and shown in the attached drawings, but should be understood as being consistent with and supported by the attached claims so that the claims have the most complete and fair scope.

Claims

1. A permanent magnet assembly for a non-commutated linear actuator, the permanent magnet assembly comprising: Core structure; as well as a permanent magnet having a first magnetic pole and a second magnetic pole, Wherein, the magnetic core structure comprises: a central core connected to the first pole of the permanent magnet; an outer hollow portion connected to the second magnetic pole of the permanent magnet; and a gap region, located between the central core and the outer hollow portion, wherein the magnetic core structure is configured so that the magnetic flux generated by the permanent magnet flows between the central core portion and the outer hollow portion via the gap region, and Wherein, the magnetic core structure includes one or more protrusions extending into the gap region.

2. The permanent magnet assembly according to claim 1, characterized in that: The one or more protrusions of the magnetic core structure include one or more core protrusions extending radially outward from the central core into the gap region.

3. A permanent magnet assembly according to any one of the preceding claims, characterized in that The one or more protrusions of the magnetic core structure include one or more hollow portion protrusions extending radially inwardly from the outer hollow portion into the gap region.

4. A permanent magnet assembly according to claim 3, when appended to claim 2, characterized in that At least one of the one or more core protrusions corresponds to and is aligned with a corresponding one of the one or more hollow protrusions.

5. A permanent magnet assembly according to any one of the preceding claims, characterised in that The central core has a substantially circular, substantially oval, or substantially square axial cross-section.

6. A permanent magnet assembly according to any one of the preceding claims, characterised in that The outer hollow portion has a substantially circular, substantially oval, or substantially square axial cross-section, and Wherein, the outer hollow portion includes at least one elongated slot along its length to allow access to the gap area.

7. The permanent magnet assembly according to any one of claims 2 to 6, characterized in that: The one or more core protrusions may have a substantially circular, substantially oval, or substantially square axial cross-section.

8. The permanent magnet assembly according to any one of claims 3 to 7, characterized in that: The one or more hollow protrusions have a substantially circular, substantially oval, or substantially square axial cross-section, and Wherein the hollow portion protrusion includes at least one elongated slot along its length to allow access to the gap region.

9. The permanent magnet assembly according to any one of claims 3 to 8, characterized in that: The one or more core protrusions include a plurality of core protrusions, and / or Wherein, the one or more hollow protrusions include a plurality of hollow protrusions.

10. The permanent magnet assembly according to claim 9, characterized in that: Each of the plurality of core protrusions is spaced apart from an adjacent core protrusion by a second distance, and Each of the plurality of hollow portion protrusions is spaced apart from an adjacent hollow portion protrusion by the second distance.

11. The permanent magnet assembly according to any one of claims 2 to 9, characterized in that: Further included is a filler material, wherein the filler material is positioned to cover sides of the one or more protrusions.

12. The permanent magnet assembly according to claim 11, characterized in that: When attached to claim 9 or 10, wherein the filling material is configured to completely fill the spaces between adjacent core protrusions among the plurality of core protrusions, and The filling material is configured to completely fill the space between adjacent hollow protrusions among the plurality of hollow protrusions.

13. The permanent magnet assembly according to claim 11 or 12, characterized in that: The filling material includes resin.

14. A non-commutating linear actuator having: fixing members; and a movable member configured to move in a longitudinal direction relative to the fixed member, in, The fixing member comprises a permanent magnet assembly as claimed in any one of claims 1 to 12, and Wherein, the movable component is located in the air gap area of ​​the permanent magnet assembly.

15. The non-commutated linear actuator according to claim 14, characterized in that The movable member includes at least one electrically conductive winding.

16. The non-commutated linear actuator according to claim 15, characterized in that The movable member comprises a structure comprising at least one of the following materials: carbon fiber, thermoplastic, thermosetting plastic, or synthetic fiber material, and Wherein, the at least one conductive winding is wound around the structure.

17. The non-commutated linear actuator according to claim 15 or 16, characterized in that When dependent on claim 8, further comprising an electrical interface configured to connect said at least one conductive winding to a power source through said at least one elongated slot.

18. The non-commutated linear actuator according to claim 17, characterized in that The electrical interface includes at least one flexible conductive strip configured to transfer power from the power source to the at least one conductive winding on the movable member.

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