Electromagnetic actuator

Abstract

The electromagnetic actuator comprises a stator extending in a first direction and a movable member movable in the first direction. The movable member comprises a yoke, a housing, a bolt, a main pole magnet arranged such that its magnetic pole is oriented perpendicularly to the yoke, and a parapole magnet arranged such that its magnetic pole is oriented non-perpendicularly to the yoke. The main pole magnet and the parapole magnet are fixed to the yoke with an adhesive, the yoke and the housing are fastened with the bolt, and the number of bolts in the projected area of ​​the main pole magnet is less than the number of bolts in the projected area of ​​the parapole magnet.

Description

Technology Field

[0001] The present disclosure relates to an electromagnetic actuator comprising a stator and a movable member. Background Technology

[0002] Conventionally, in driving devices requiring precise positioning, such as photolithography equipment used in the manufacture of semiconductor devices, machine tools, and railway systems, electromagnetic actuators that perform linear motion are used. For example, the electromagnetic actuator disclosed in Japanese Patent Publication No. 2003-116260 comprises a stator having a fixed coil and a movable member having a movable magnet. By flowing current through the coil to generate magnetic flux, the movable member can be driven by generating a driving force on the movable magnet through interaction with the magnetic field of the magnet.

[0003] Recently, high-speed driving is required to improve the productivity of devices. To achieve high-speed driving, electromagnetic actuators need to generate higher thrust, and the structure of the actuator generating high thrust is subjected to high loads associated with that generated thrust.

[0004] For this reason, the load received by the operator concentrates stress around the bolts installed between the parts, propagating the stress to the adhesive holding the magnets in place, which may cause the adhesive to peel off.

[0005] In one aspect of the present disclosure, an electromagnetic actuator is provided having a stator extending in a first direction and a movable member moving in the first direction. The movable member comprises a yoke, a housing, a main pole magnet, and a parapole magnet. The main pole magnet is configured to orient a magnetic pole in a direction perpendicular to the yoke. The parapole magnet is configured to orient a magnetic pole in a direction not perpendicular to the yoke. The main pole magnet and the parapole magnet are fixed to the yoke with an adhesive. The yoke and the housing are fastened with a plurality of bolts. A first group of bolts of the plurality of bolts is installed in the projected area of ​​the main pole magnet. A second group of bolts of the plurality of bolts is installed in the projected area of ​​the parapole magnet. The first group of bolts is fewer than the second group.

[0006] The features of the present disclosure will become apparent from the description of the following embodiments with reference to the accompanying drawings. Brief explanation of the drawing

[0007] FIGS. 1a and 1b are drawings illustrating examples of the configuration of an electromagnetic actuator according to a first embodiment of the present disclosure. FIG. 2 is a drawing illustrating an example of the configuration of a part of a moving part according to a first embodiment. FIG. 3 is a drawing illustrating an example of the configuration of an electromagnetic actuator according to a second embodiment. FIG. 4 is a drawing illustrating an example of the configuration of an electromagnetic actuator according to a third embodiment. FIGS. 5A and 5B are drawings illustrating other configuration examples of an electromagnetic actuator according to a fourth embodiment. Specific details for implementing the invention

[0008] Hereinafter, preferred embodiments of the present disclosure will be described using embodiments with reference to the accompanying drawings. In each drawing, the same reference numerals are assigned to identical members or elements. For brevity, redundant descriptions are included by reference or simplified.

[0009] <First Embodiment>

[0010] FIGS. 1a and 1b are drawings illustrating an example configuration of an electromagnetic actuator according to a first embodiment of the present disclosure. FIG. 1a is a cross-sectional view along a plane including an axis (13), and FIG. 1b is a cross-sectional view along a plane perpendicular to the axis (13).

[0011] As illustrated in FIG. 1a and FIG. 1b, the electromagnetic actuator according to the present embodiment has a stator (1) and a movable member (2). The stator (1) has a columnar shape extending in a first direction (longitudinal direction) (3) and consists of a support member (10) along an axis center and a plurality of coils (4) disposed on the outer surface of the support member (10). The movable member (2) can move in the first direction (3).

[0012] An insulating member, a yoke, or both may be disposed between the support member (10) and the coil (4). The support member (10) functions as a base that supports the coil (4). The support member (10) may also have a coil cooling channel installed inside to prevent the temperature of the coil from rising.

[0013] For example, a coil cooling channel for flowing a cooling medium may be installed inside or on the surface of the housing (5) of the actuator (2). Thus, by installing a cooling channel for flowing a cooling medium in at least one of the stator (1) and the actuator (2), the temperature rise of the electromagnetic actuator may be suppressed.

[0014] The movable member (2) has a hollow shape that is non-contactually surrounded by the outer periphery of the stator (1) in a plane perpendicular to the first direction (3) and penetrates in the first direction (3). As shown in FIG. 1b, two pairs of opposing magnets (6) are arranged on the inner surface of the movable member (2).

[0015] A plurality of magnets (6) are provided with a co-polar magnet (6b) magnetized in the direction of the axis (13) as indicated by the direction of the magnetic pole (9), and a main pole magnet (6a) magnetized in a direction perpendicular to the axis (13), and are arranged to generate an alternating magnetic field on the inner surface of the movable member.

[0016] In addition, in this embodiment, the plurality of magnets (6) are arranged in a Halbach array that generates a roughly sinusoidal magnetic field for one cycle. As shown in FIG. 1b, in this embodiment, the stator (1) and the movable member (2) have a roughly rectangular cross-section, but are not limited to this. For example, a circular or elliptical shape may be used, and the cross-sectional shape is not limited to the shape shown in FIG. 1b.

[0017] Each magnet (6) has a portion or all of its surface with respect to the yoke (8) with the adhesive layer (7) in between, and the yoke (8) is held by the housing (5) and the bolt (11). That is, the main pole magnet (6a) and the interpolation magnet (6b) are fixed to the yoke (8) with adhesive, and the yoke (8) and the housing (5) are fastened with the bolt (11).

[0018] Thus, the movable member (2) according to the present embodiment has a yoke (8), a housing (5), a bolt (11), a main pole magnet (6a) arranged such that its magnetic pole is oriented perpendicular to the yoke (8), and a secondary pole magnet (6b) arranged such that its magnetic pole is oriented non-perpendicular to the yoke (8). Additionally, when a cooling channel is installed to flow a cooling medium inside or on the surface of the housing (5), the bolt (11) is positioned to avoid the cooling channel.

[0019] A plurality of coils (4) have a plurality of phases (in this example, two phases, A and B). In addition, in the driving method of the linear motor according to the present embodiment, a sine wave is supplied to a plurality of coils (4) to control the current and magnetic flux to be orthogonal. Furthermore, by switching the coils so that a sine wave is supplied only to the coil among the plurality of coils (4) that faces the plurality of magnets (6), heat generation is reduced.

[0020] In the electromagnetic actuator according to the present embodiment, in order to efficiently utilize the magnetic field generated by the coil (4) as a driving force, the gap between the coil (4) and the magnet (6) is reduced as much as possible in size.

[0021] FIG. 2 is a drawing illustrating an example of the configuration of a part of a movable member (2) according to a first embodiment. As described above, the magnet (6) is configured in a Halbach array that generates an approximately sinusoidal magnetic field by means of a co-pole magnet (6b) magnetized in the direction of the axis (13) and a main pole magnet (6a) magnetized in a direction perpendicular to the axis (13).

[0022] At this time, the direction of the force (12) acting on each magnet (6) due to the magnetic force of the coil (4) generates a force that causes the main pole magnet (6a) to detach from the yoke (8) and the adhesive layer (7) to detach. In addition, for the auxiliary pole magnet (6b), a force that compresses the adhesive layer (7) is generated in a direction that attracts it to the yoke (8). That is, if the adhesive layer (7) is damaged, the main pole magnet (6a) is more likely to have the adhesive layer (7) detached and fall off than the auxiliary pole magnet (6b).

[0023] Meanwhile, when thrust is generated by energizing the coil (4), the housing (5) is deformed due to the inertial force generated between the connected driving object and the housing (5), thereby generating stress. At this time, the inertial force causes deformation at the end of the movable member (2) in the direction of the axis (13).

[0024] The generated stress is propagated to the bolt (11) through the housing (5) and concentrated around the bolt (11) of the yoke (8). Because of this, the adhesive layer (7) may be destroyed in the part of the adhesive layer (7) closer to the bolt (11), and the adhesive may peel off.

[0025] Accordingly, in the present embodiment, bolts (11) (11a, 11b, 11c, 11d) for fastening the housing (5) and the yoke (8) are in the projected area (PA) of the interpolated magnet (6b). IM ) placed in the projection area (PA) of the main pole magnet (6a) installed at the end in the direction of the axis (13) of the movable member (2). MPM It is not placed in ).

[0026] When the actuator (2) is deformed due to inertia and stress is generated in the actuator (2), a bolt (11) is placed at a location where the deformation of the actuator (2) is small, and a bolt (11) is not placed at a location where the deformation is larger.

[0027] Therefore, even if a force is applied to the magnet (6) in the direction of adhesive peeling, that is, in the first direction (longitudinal direction) (3), concentrated stress generated around the bolt (11) does not occur near the main pole magnet (6a), thereby preventing the magnet (6) from falling off.

[0028] <Second Embodiment>

[0029] FIG. 3 is a drawing illustrating an example of the configuration of an electromagnetic actuator according to a second embodiment. In the actuator (2) according to the second embodiment, a bolt (11) for connecting the yoke (8) and the housing (5) is positioned not only in the projected area of ​​the interpol magnet (6b) but also in the projected area of ​​the main pole magnet (6a).

[0030] However, the number of bolts (11) placed in the projection area of ​​the main pole magnet (6a) is less than the number of bolts placed in the projection area of ​​the auxiliary pole magnet (6b). That is, the number of bolts (11) in the projection area of ​​the main pole magnet (6a) is less than the number of bolts (11) in the projection area of ​​the auxiliary pole magnet (6b).

[0031] The number of bolts (11) in the projected area of ​​the main pole magnet (6a) placed at the end of the movable member (2) is set to be less than the number of bolts (11) in the projected area of ​​the auxiliary pole magnet (6b) placed at a location other than the end of the movable member (2). In the second embodiment, the fact that the number of bolts (11) placed in the projected area of ​​the main pole magnet is less includes cases where no bolts are installed in the projected area of ​​the main pole magnet, as in the first embodiment.

[0032] The number of bolts (11) connecting the yoke (8) and the housing (5) ensures sufficient fastening force to hold the housing (5) in the yoke (8). Therefore, this embodiment is effective in cases where all bolts (11) cannot be placed in the projected area of ​​the interpolation magnet (6b) due to space limitations.

[0033] In this embodiment, the number of bolts (11) placed in the projected area of ​​the main pole magnet (6a) is less than the number of bolts (11) placed in the projected area of ​​the auxiliary pole magnet (6b). Therefore, when a force in the direction of adhesive peeling is applied to the magnet (6), concentrated stress is not generated around the bolts (11) in the vicinity of the main pole magnet (6a), which is more likely to detach from the adhesive layer (7) than the auxiliary pole magnet (6b), thereby preventing the magnet (6) from detaching.

[0034] Multiple bolts may be arranged in the projection area of ​​the main pole magnet (6a) such that the spacing between multiple bolts in the projection area of ​​the main pole magnet (6a) is wider than the spacing between multiple bolts in the projection area of ​​the auxiliary pole magnet (6b). Additionally, for example, when multiple bolts (11) (three or more) are arranged along the axis (13) in the projection area of ​​the main pole magnet (6a), the spacing between the three or more bolts (11) may be different from each other.

[0035] For example, the two bolts (11) at the end of the movable member (2) may be arranged such that the spacing between the two bolts (11) at the end of the movable member (2) is wider than the spacing between the remaining bolts (11). That is, in the projected area of ​​the main pole magnet (6a), the spacing between the bolts (11) at the end of the movable member (2) may be wider than the spacing between the remaining bolts (11). Accordingly, the concentrated stress generated around the bolts (11) at the end is reduced.

[0036] In this embodiment, no bolt (11) is placed in the projected area of ​​the main pole magnet (6a) other than the end of the first direction (3) (i.e., axial direction) of the movable member (2). This prevents the main pole magnet (6a) from falling off by reducing the concentrated stress at the main pole magnet (6a) other than the end of the axial direction of the movable member (2).

[0037] In order to further increase the fastening force holding the magnet (6) and the yoke (8), the number of bolts placed in the projected area of ​​the main pole magnet (6a) other than the axial end of the movable member (2) is less than the number of bolts (11) placed in the projected area of ​​the auxiliary pole magnet (6b).

[0038] FIG. 3 illustrates bolts (11) arranged on the surface of the housing (5) in the direction of the axis (13) which is perpendicular to the axis (13) on the surface of the housing (5). Even in this case, the number of bolts (11) arranged in the projected area of ​​the main pole magnet (6a) is less than the number of bolts (11) arranged in the projected area of ​​the interpol magnet (6b).

[0039] The arrangement pattern of a plurality of bolts (11) placed in the projection area of ​​the main pole magnet (6a) on the surface of the housing (5) may be different from the arrangement pattern of a plurality of bolts (11) placed in the projection area of ​​the auxiliary pole magnet (6b). The two-dimensional arrangement pattern is represented, for example, by a predetermined spacing of a plurality of bolts (11) and a distance from the axis (13).

[0040] For this reason, stress concentration may be prevented by reducing the density of the plurality of bolts (11) placed in the projection area of ​​the main pole magnet (6a) to less than the density of the plurality of bolts (11) placed in the projection area of ​​the auxiliary pole magnet (6b).

[0041] In the case where a cooling channel is installed to flow a cooling medium inside or on the surface of the housing (5), a plurality of bolts (11) placed in the projected area of ​​the main pole magnet (6a) are positioned to avoid the cooling channel.

[0042] In the second embodiment, when the housing (5) is deformed due to inertia and stress is generated in the movable member (2), a plurality of bolts (11) are placed at locations where the deformation of the movable member (2) is small, and fewer bolts (11) are placed at locations where the deformation is larger. Therefore, stress generated around the bolts (11) is not concentrated near the main pole magnet (6a), thereby preventing the magnet (6) from falling off.

[0043] <Third Embodiment>

[0044] FIG. 4 is a drawing illustrating an example of the configuration of an electromagnetic actuator according to a third embodiment. The actuator (2) according to the third embodiment is composed of a main pole magnet (6a) magnetized in a direction perpendicular to the axis and an oblique pole magnet (6c) magnetized in an axial direction relative to the main pole magnet (6a).

[0045] In this embodiment, a Halbach arrangement is formed in which a complementary magnet (fourth pole) (6c) is placed between the main pole magnets (6a), and two complementary magnets (fourth pole) (6c) are placed between the main pole magnets (6a) such that the direction of the magnetic poles is reversed axially with respect to each other.

[0046] Accordingly, an electromagnetic actuator capable of outputting higher thrust is realized. In addition, in the case of a Halbach array, the number of interpoles with more precisely specified magnetic pole directions can be increased.

[0047] As in the first embodiment, the bolt (11) used for fastening the housing (5) and the yoke (8) is placed in the projected area of ​​the interpolation magnet (fourth pole) (6c) and is not placed in the projected area of ​​the main pole magnet (6a), which is highly likely to detach from the adhesive layer (7).

[0048] However, as in the second embodiment, the number of bolts (11) placed in the projection area of ​​the main pole magnet (6a) may be set to be less than the number of bolts (11) placed in the projection area of ​​the auxiliary pole magnet (6c).

[0049] <Fourth Embodiment>

[0050] FIGS. 5A and 5B are drawings illustrating other configuration examples of an electromagnetic actuator according to a fourth embodiment. FIG. 5A is a cross-sectional view illustrating an configuration example along a plane including an axis (13), and FIG. 5B is a drawing illustrating an example of a configuration viewed from below the stator toward the housing (5).

[0051] The stator (1) according to the fourth embodiment has a support member (10) and a plurality of coils (4). For example, as shown in FIGS. 5a and 5b, the coils (4) are arranged such that a portion of the winding direction is oriented toward the first direction (3), and the direction of the magnetic pole generated by the coils (4) is orthogonal to the first direction (3). The movable member (2) has a magnet (6) placed on its inner surface.

[0052] Here, as in the first to third embodiments, the main pole magnet (6a) and the interpol magnet (6b) are arranged in a Halbach arrangement, and the bolt (11) for fastening the housing (5) and the yoke (8) is also not placed in the projection area of ​​the main pole magnet (6a), which is highly likely to detach from the adhesive layer (7), as in the first to third embodiments, but is placed in the projection area of ​​the interpol magnet (6b).

[0053] As in the second embodiment above, the number of bolts (11) placed in the projection area of ​​the main pole magnet (6a) may be set to be less than the number of bolts (11) placed in the projection area of ​​the auxiliary pole magnet (6b).

[0054] The fourth embodiment has a simpler structure than the first embodiment. Accordingly, in addition to reducing the occupied area, it makes manufacturing easier and reduces costs.

[0055] Although the present disclosure has been described with reference to embodiments, it will be understood that the present disclosure is not limited to the embodiments disclosed above. The scope of the claims below should be broadly interpreted to include all variations and equivalent structures and functions. For example, an electromagnetic actuator may be used in which a fixed magnet having a cross-sectional shape, for example, rectangular shape is used as a stator, and a movable coil surrounding the fixed magnet is used as a movable.

[0056] In addition, as described above, an electromagnetic actuator using a fixed coil or a movable magnet with a circular or elliptical cross-sectional shape may be adopted, and the cross-sectional shape or configuration of the stator (1) and the movable member (2) may be appropriately changed.

[0057] This application claims the benefits of Japanese Patent Application No. 2025-028186 filed on February 25, 2025, which is incorporated herein by reference in its entirety.

Claims

Claim 1 An electromagnetic actuator comprising a stator extending in a first direction; and a movable member moving in the first direction, wherein the movable member comprises a yoke, a housing, a main pole magnet, and a parapole magnet, wherein the main pole magnet is configured to orient a magnetic pole in a direction perpendicular to the yoke, and the parapole magnet is configured to orient a magnetic pole in a direction not perpendicular to the yoke, wherein the main pole magnet and the parapole magnet are fixed to the yoke with an adhesive, and the yoke and the housing are fastened with a plurality of bolts, wherein a first group of bolts of the plurality of bolts is installed in a projected area of ​​the main pole magnet, and a second group of bolts of the plurality of bolts is installed in a projected area of ​​the parapole magnet, and wherein the first group of bolts is less than the second group. Claim 2 An electromagnetic actuator according to claim 1, wherein at least one of the stator and the actuator has a cooling channel. Claim 3 In claim 1, the stator is an electromagnetic actuator having at least one coil and a support member. Claim 4 An electromagnetic actuator according to claim 1, wherein the movable member has a hollow surrounding the outer periphery of the stator in a plane orthogonal to the first direction, and two pairs of opposing magnets are arranged on the inner surface of the movable member. Claim 5 An electromagnetic actuator according to claim 1, wherein the plurality of bolts are not disposed in the projection area of ​​the main pole magnet. Claim 6 An electromagnetic actuator according to claim 1, wherein the spacing between the bolts of the plurality of bolts in the projection area of ​​the main pole magnet is wider than the spacing between the bolts of the plurality of bolts in the projection area of ​​the interpol magnet. Claim 7 An electromagnetic actuator according to claim 1, wherein the spacing between the bolts of the plurality of bolts at the end of the movable member of the projection area of ​​the main pole magnet is wider than the spacing between the remaining bolts of the plurality of bolts. Claim 8 An electromagnetic actuator according to claim 1, wherein the number of bolts in the projected area of ​​the main pole magnet disposed at the end of the actuator is less than the number of bolts in the projected area of ​​the interpol magnet disposed at a location other than the end of the actuator. Claim 9 An electromagnetic actuator comprising a stator extending in a longitudinal direction; and a movable member moving in the longitudinal direction, wherein the movable member comprises a yoke, a housing, a main pole magnet, and a parapole magnet, and a plurality of bolts connecting the yoke and the housing are divided into a first group and a second group, wherein the first group is installed in the projection area of ​​the main pole magnet and the second group is installed in the projection area of ​​the parapole magnet, and the number of bolts in the second group is greater than that in the first group. Claim 10 An electromagnetic actuator according to claim 9, wherein the main pole magnet is configured to orient the magnetic poles in a direction perpendicular to the longitudinal direction, and the interpol magnet is configured to orient the magnetic poles in a direction not perpendicular to the longitudinal direction. Claim 11 In claim 9, an electromagnetic actuator in which the yoke extends in the longitudinal direction. Claim 12 An electromagnetic actuator according to claim 9, further comprising an adhesive configured to fix the yoke to at least one of the main pole magnet or the interpole magnet. Claim 13 An electromagnetic actuator according to claim 9, further comprising a cooling channel installed in at least one of the stator or the actuator.

Images