JP2012055071A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator capable of extending the lifetime of a support mechanism for supporting a movable element and improving positioning accuracy of the movable element, in the structure in which the movable element is movably cantilever-supported.SOLUTION: A linear actuator includes: a movable element 2 that is movably cantilever-supported at a support base along a predetermined reciprocation direction; a stator core 10 that has stator-side opposing parts 10b so as to form a first gap gp1 and a second gap gp2 between the stator-side opposing parts and the portions displaced from the support base of the movable element 2; and permanent magnets 12a, 12b, 12c, and 12d that are oppositely disposed so as to reverse each magnetic pole of a surface on the opposing part of the other permanent magnet, and the movable element 2 is reciprocally moved by applying power to a coil 11. Electromagnetic attraction forces F3 and F4, mutually attracting the movable element 2 in opposite directions, are generated in the first gap gp1 and the second gap gp2, respectively. Different strength is set to the electromagnetic attraction forces F3 and F4, and thereby providing a electromagnetic supporting unit 3 electromagnetically supporting the movable element 2 by a biasing force obtained by the difference between the electromagnetic attraction forces F3 and F4.

Description

  The present invention relates to a linear actuator that reciprocally moves a mover supported in a cantilever manner, and particularly relates to a linear actuator that is well treated for a load applied to the mover.

  A linear actuator such as a reciprocating motor mainly includes a magnetic circuit that reciprocates a movable element when energized, as exemplified in Patent Document 1. The magnetic circuit is arranged along the reciprocating direction in a stator-side facing portion facing the mover core of the stator core and the mover core and the stator core made of a magnetic material, and faces each mover core. Consists of a plurality of element parts including a pair of permanent magnets with reversed magnetic poles on the surface to be wound and a coil wound around the stator core, and the magnetic flux generated by energizing the coils forms a pair. The mover is reciprocated by weakening the magnetic flux generated by a magnet located in a required direction among the permanent magnets and strengthening the magnetic flux generated by the other magnet.

JP 2003-339147 A

  By the way, there is a restriction or a requirement that a support mechanism such as a bearing for movably supporting the mover cannot be disposed on one of the movers, and a configuration in which the mover is cantilevered may be employed. In such a configuration in which the mover is cantilevered, gravity, an external force applied to the mover, and the like act on the support mechanism as an unbalanced load, so the life of the support mechanism is shortened.

  In addition, the mover bends due to external load or gravity, and the positioning accuracy of the mover is reduced. In particular, when a workpiece is attached to the mover, the load of the workpiece is applied to the mover, so that the mover is easily bent, and the positioning accuracy of the workpiece and the mover is significantly impaired.

  Such a problem is not limited to the movable iron core type in which the mover is composed only of the iron core among the component parts constituting the magnetic circuit as described above, and the mover constituting the mover is a permanent magnet. The same can be said for a movable magnet type including

  The present invention has been made paying attention to such problems, and its purpose is to determine the life of the support mechanism that supports the mover and the positioning of the mover in a configuration in which the mover is movably cantilevered. To provide a linear actuator with improved accuracy.

  In order to achieve this object, the present invention takes the following measures.

  In other words, the linear actuator of the present invention is provided between the mover that is cantilevered at the support base end so as to be movable along a predetermined reciprocating direction, and a portion of the mover that is displaced from the support base end. A stator core having a pair of stator-side facing parts forming a gap and a second gap, a coil wound around the stator core, and a movable part facing the stator-side facing part of the mover Permanent magnets that are paired with either the child-side facing portion or the stator-side facing portion of the stator core along the reciprocating direction, and are paired by reversing the magnetic poles of the surfaces facing the opposite-side facing portions. The magnetic flux generated by energizing the coil is weakened by the magnet located in the required direction among the paired permanent magnets, and the magnetic flux generated by the other magnet is strengthened to reciprocate the mover. To the coil Set the difference in the strength of the electromagnetic attraction force that pulls the mover in the opposite direction to each other, which is expressed in the first gap and the second gap by the magnetic flux generated by the energization or the permanent magnet, respectively. The electromagnetic support part which electromagnetically supports the site | part displaced from the support base end among the needle | mover with the urging | biasing force obtained by is provided.

  In this way, by setting the difference in the strength of the electromagnetic attracting force that pulls the mover in the opposite direction to each other, expressed in the first and second gaps, the biasing force obtained by the difference in each electromagnetic attracting force Since the electromagnetic support part that electromagnetically supports the part of the mover displaced from the support base end is provided, the mover is supported at at least two points, and the unbalanced load applied to the support mechanism that supports the mover is reduced. This can reduce the life of the support mechanism. Moreover, since the mover is supported at at least two points, it is possible to reduce or eliminate the bending of the mover due to the load acting on the mover, and to improve the positioning accuracy of the mover and the workpiece provided on the mover. Become.

  In order to appropriately cope with the above-mentioned problem caused by the gravity acting on the movable element and the workpiece provided on the movable element, out of the electromagnetic attraction force acting on the first gap and the second gap, the anti-gravity direction side It is preferable that one electromagnetic attraction force that pulls the mover toward the side is set to be stronger than the other electromagnetic attraction force that pulls the mover toward the gravity direction.

  As described above, the present invention sets the difference in the strength of the electromagnetic attracting force that draws the mover in the opposite direction to each other, and expresses the difference between the respective electromagnetic attracting forces. Since the electromagnetic support part that electromagnetically supports the part of the mover displaced from the support base end by the urging force obtained by the above is provided, the mover is supported at least at two points, and the support that supports the mover is provided. It is possible to reduce the unbalanced load applied to the mechanism and improve the life of the support mechanism. Moreover, since the mover is supported at at least two points, it is possible to reduce or eliminate the bending of the mover due to the load acting on the mover, and to improve the positioning accuracy of the mover and the workpiece provided on the mover. Become. Therefore, it is possible to improve the driving accuracy and reliability of the linear actuator.

The cross-sectional view which shows typically the linear actuator which concerns on one Embodiment of this invention. FIG. 2 is a cross-sectional view of the linear actuator shown in FIG. The figure which shows the needle | mover of the actuator typically. Explanatory drawing regarding operation | movement of the actuator. Explanatory drawing regarding the electromagnetic attractive force which acts on the 1st and 2nd gap. The figure which shows the structure of the linear actuator which concerns on other embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the linear actuator of the present embodiment includes a stator 1 and a mover 2 configured to be movable relative to the stator 1 along the reciprocating direction (X direction). Have The movable base 2 is cantilevered at the support base end 2 b by the support mechanism 14. As shown in FIG. 3, the linear actuator of this embodiment is used to attach a workpiece W such as a wire bonder nozzle to the mover 2 and configure the drive unit of these devices.

  As shown in FIGS. 1 and 2, the stator 1 has a magnetic stator core 10 having a stator-side facing portion 10 b, 10 b having a C-shaped cross section and a pair of end faces facing each other, It has a coil 11 wound around the stator core 10 and a permanent magnet 12 attached to the stator side facing portion 10b. The stator core 10 is configured by stacking and fixing a plurality of stator core plates (not shown) along the axial direction. Between the stator-side facing portions 10b, 10b facing each other, a portion of the mover 2 displaced from the support base end 2b supported by the support mechanism 14 is disposed, and a pair of stator-side facing portions 10b is formed. A first gap gp1 and a second gap gp2 are formed between 10b and the mover 2. A portion of the mover 2 that faces the stator side facing portion 10b may be referred to as a mover side facing portion 20b in the following description.

  As shown in FIGS. 1 and 2, the coils 11 constituting the stator 1 are obtained by attaching a pair of coils 11, 11 having the same number of turns to the stator side facing portions 10 b, 10 b. 11 is arranged at a position facing each other across the first gap gp1 and the second gap gp2, and a magnetic flux for moving the mover 2 by energization is generated in the first gap gp1 and the second gap gp2. Is.

  As shown in FIGS. 1 and 2, the permanent magnet 12 constituting the stator 1 is a stator-side facing portion along a reciprocating direction (X direction) of a pair of permanent magnets 12 a and 12 b (12 c and 12 d). 10b and 10b are arranged, and the magnetic poles of the surfaces facing the respective movable elements 2 (movable element side facing portions 20b) are reversed. Specifically, a pair of permanent magnets 12a and 12b is attached to the stator side facing portion 10b that forms the first gap gp1 between the mover 2 and the mover side facing portion 20b. Paired permanent magnets 12c and 12d are attached to the stator-side facing portion 10b that forms the second gap gp2 between the mover 2 and the armature-side facing portion 20b.

  As shown in FIGS. 1 to 3, the mover 2 has a substantially rectangular shape and is disposed at a position where the distal end 2 a side which is a free end is sandwiched between the stator-side facing portions 10 b and 10 b of the stator core 10. The end 2b side is attached to a support mechanism 14 which is a bearing with a fixing tool bo such as a bolt shown in FIG. 3, and is configured to be linearly movable along the reciprocating direction (X direction) in a cantilevered support state. Specifically, as shown in FIG. 3, the mover 2 is a magnetic mover core in which the portions facing the stator-side facing portions 10b and 10b that make a pair are respectively movable-side facing portions 20b and 20b. 20 and a connecting member 21 made of a non-magnetic material such as a resin for associating (connecting) the mover core 20 with the support mechanism 14. As shown in FIG. 1, the mover core 20 is movable by causing an electromagnetic force to act on the mover 2 by expressing the magnetic flux mf together with the stator core 10, the coil 11, and the permanent magnet 12 constituting the stator 1. It is a part of a plurality of component parts constituting the magnetic circuit mc for reciprocating the child 2. In the present embodiment, among the plurality of element parts (stator core 10, coil 11, permanent magnet 12, mover core 20) constituting the magnetic circuit mc, the element parts constituting the mover 2 are referred to as iron cores. A movable core type actuator having only 20 is constructed.

  As shown in FIG. 3, the connecting member 21 constituting the mover 2 has a dimension w1 on the distal end 2a side (anti-support mechanism side) of the mover 2 and a dimension w2 on the base end 2b side (support mechanism 14 side). By forming the taper portion 21a to be smaller than that, the center of gravity of the mover 2 is configured to be as close as possible to the support mechanism 14 side. As described above, in the configuration in which the support mechanism 14 cantilever-supports the mover 2, the stability with respect to vibration during acceleration / deceleration increases as the center of gravity of the mover 2 approaches the support mechanism 14. If the support mechanism 14 side and the anti-support mechanism side of the mover 2 are formed asymmetrically so that the center of gravity of the child 2 is brought closer to the support mechanism 14 side, the vibration generated in the mover 2 during acceleration or deceleration can be reduced and moved. The child 2 and the work W can be driven efficiently.

  Since the operation of the actuator having the above-described configuration is the same as that of Patent Document 1, detailed description thereof is omitted. However, when the coil 11 is not energized, as shown in FIG. Magnetic fluxes mf1 and mf2 having different directions are expressed by the permanent magnets 12a and 12b (12c and 12d) that make a pair in the gaps gp1 and gp2. As shown in FIG. 4B, when the coil 11 is energized in a certain direction (positive direction), the energization of the coil 11 generates the magnetic flux mf shown in FIG. 1, and the permanent magnets 12 forming each pair. The magnetic flux mf1 in the same direction as the magnetic flux mf generated by energizing the coil 11 is increased, the other magnetic flux mf2 is weakened, and the electromagnetic force F1 is applied to the mover 2 (movable core 20). By acting, the mover 2 moves in the direction of increasing magnetic flux (X1 direction). On the other hand, as shown in FIG. 4 (c), when the coil 11 is energized in the reverse direction opposite to the normal direction, the electromagnetic force F2 acts in the reverse direction (X2 direction), and the mover 2 moves in the X2 direction. That is, in the magnetic circuit mc, the magnet 12a (12b) [12c (12d)] in which the magnetic flux mf generated by energizing the coil 11 is positioned in a required direction among the pair of permanent magnets 12a and 12b [12c and 12d]. The magnetic force mf2 (mf1) generated by the second magnet 12 is weakened, and the magnetic flux mf1 (mf2) generated by the other magnet 12b (12a) [12d (12c)] is strengthened, so that the electromagnetic force F1 (F2) is applied to the mover 2 2 is reciprocated.

  Further, as shown in FIG. 5A, the magnetic circuit mc reciprocates back and forth between the first gap gp1 and the second gap gp2 by the magnetic flux generated by the permanent magnet 12 when the coil 11 is not energized. Electromagnetic attractive forces F3 and F4 that are perpendicular to the direction (X direction) and in opposite directions are developed. That is, the magnetic flux mfa · mfb is generated in the first gap gp1 by the pair of permanent magnets 12a and 12b arranged in the stator-side facing portion 10b positioned on the anti-gravity direction side of the mover core 20, and the magnetic flux mfa · An electromagnetic attractive force F3 that draws the mover 2 toward the anti-gravity direction side is generated by mfb. On the other hand, the magnetic flux mfc · mfd is generated in the second gap gp2 by the pair of permanent magnets 12c and 12d arranged in the stator side facing portion 10b located on the gravity direction side of the mover core 20, and the magnetic flux mfc · An electromagnetic attractive force F4 that draws the mover 2 toward the gravitational direction side is generated by mfd. The electromagnetic attractive forces F3 and F4 acting on the first gap gp1 and the second gap gp2 work along the vertical direction that is orthogonal to the reciprocating direction (X direction). F4 pulls the mover 2 in opposite directions. As shown in FIG. 5A, when the strengths of the four permanent magnets 12a, 12b, 12c, and 12d are all equal, the strengths of the two electromagnetic attractive forces F3 and F4 generated by these permanent magnets 12 are Since there is no difference, these two electromagnetic attractive forces F3 and F4 are in balance with each other.

  Incidentally, as shown in FIG. 1, in the configuration in which the mover 2 is cantilevered by the support mechanism 14, gravity, an external force applied to the mover 2, etc., is applied to the support mechanism 14 as an unbalanced load g. There is a short-lived defect. In addition, the mover 2 is bent by a load or gravity received from the outside, and the free end (tip 2a) side of the mover 2 is dropped, and the positioning accuracy of the mover 2 is reduced. In particular, when the work W is attached to the free end (tip 2a) side of the mover 2, the mover 2 is easily bent by the load of the work W, and the positioning accuracy of the work W and the mover 2 is significantly impaired.

  Therefore, in this embodiment, as shown in FIG. 1 and FIG. 5B, a difference is set in the strengths of the electromagnetic attractive forces F3 and F4 expressed in the first gap gp1 and the second gap gp2, respectively. The electromagnetic support portion 3 is provided that electromagnetically supports a portion of the mover 2 displaced from the support base end 2b by an urging force (F3-F4) obtained by the difference between the electromagnetic attractive forces F3 and F4. That is, the electromagnetic support portion 3 is one of the electromagnetic attractive forces that urge the mover 2 toward the antigravity direction of the electromagnetic attractive forces F3 and F4 acting on the first gap gp1 and the second gap gp2. By setting F3 stronger than the other electromagnetic attraction force F4 that urges the mover 2 toward the gravity direction, the mover 2 moves toward the antigravity direction due to the difference between the electromagnetic attraction forces F3 and F4. The mover 2 is electromagnetically supported by the urging force (F3-F4) that urges the. Specifically, the strength of the permanent magnets 12a and 12b forming a pair that develops the electromagnetic attractive force F3 in the first gap gp1 is set to be permanent, and the permanent strength that forms a pair that develops the electromagnetic attractive force F4 in the second gap gp2. By making it stronger than the magnets 12c and 12d, a difference is provided in the strength of the electromagnetic attractive forces F3 and F4 acting on the first and second gaps gp1 and gp2. The strength of the urging force (F3-F4) is set so as to balance with the load g such as gravity acting on the movable element 2 or the workpiece W, external force applied to the movable element 2, as shown in FIG. Yes.

  As described above, the linear actuator of the present embodiment is displaced from the support base end 2b of the mover 2 that is cantilevered by the support base end 2b so as to be movable along a predetermined reciprocating direction. A stator core 10 having a pair of stator-side facing portions 10b and 10b forming a first gap gp1 and a second gap gp2 between the portion and a coil 11 wound around the stator core 10; The stator core 10 has a pair of inverted magnetic poles on the side facing the opposite side (movable side facing part 20b) arranged in the stator side facing part 10b along the reciprocating direction. Permanent magnets 12a and 12b (12c and 12d), and a magnet 12a (12b) positioned in a required direction among permanent magnets 12a and 12b [12c and 12d] paired with a magnetic flux mf generated by energizing the coil 11. [12 (12d)] is weakened in magnetic flux mf2 (mf1), and magnetic flux mf1 (mf2) generated in the other magnet 12b (12a) [12d (12c)] is strengthened to move the mover 2 back and forth. The strength of the electromagnetic attractive forces F3 and F4 that attract the mover 2 in the opposite directions, which are expressed in the first gap gp1 and the second gap gp2 by the magnetic fluxes mfa, mfb, mfc, and mfd generated by the permanent magnet 12, respectively. The electromagnetic support part which electromagnetically supports the part displaced from the support base end 2b of the mover 2 by the biasing force (F3-F4) obtained by the difference between the electromagnetic attraction forces F3 and F4. 3 is provided.

  In this way, a difference is set in the strength of the electromagnetic attraction forces F3 and F4 that draw the mover 2 in the opposite directions, which are expressed in the first gap gp1 and the second gap gp2, respectively. Since the electromagnetic support portion 3 that electromagnetically supports a portion of the mover 2 displaced from the support base end 2b by the biasing force (F3-F4) obtained by the difference between F3 and F4 is provided. The support mechanism 14 is supported at two points, and the life of the support mechanism 14 can be improved by reducing or eliminating the offset load g applied to the support mechanism 14 that supports the mover 2, and the mover 2 is at least at two points. Since the support is supported, it is possible to reduce or eliminate the bending of the mover 2 due to the load g acting on the mover 2 and improve the positioning accuracy of the mover 2 and the workpiece W provided on the mover 2.

  In particular, in the present embodiment, of the electromagnetic attractive force F3 and F4 acting on the first gap gp1 and the second gap gp2, one electromagnetic attractive force F3 that pulls the mover 2 toward the antigravity direction side is obtained. Since it is set to be stronger than the other electromagnetic attraction force F4 that pulls the mover 2 toward the direction of gravity, it is possible to appropriately cope with the above-described problems caused by gravity acting on the mover 2 and the workpiece W. Become.

  As mentioned above, although one Embodiment of this invention was described, the specific structure of each part is not limited only to embodiment mentioned above.

  For example, in the present embodiment, the stator core 10 is a C-shaped core having a C-shaped cross section and having end faces facing each other, but a pair that forms first and second gaps with the mover 2. As long as there is a facing portion that forms the following, it is not limited to this C-type core.

  Furthermore, as a configuration in which a difference is set in the strengths of the electromagnetic attractive forces F3 and F4 generated in the first gap gp1 and the second gap gp2, the following configuration is exemplified in addition to the configuration of the present embodiment. That is, the electromagnetic attractive force F3 and F4 acting on the mover 2 via the first gap gp1 and the second gap gp2 is also generated by the magnetic flux generated by energization of the coil 11, so that the first gap gp1 The number of turns of the coil 11 that develops the electromagnetic attractive force F3 (the coil 11 above the mover core 20) is the same as that of the coil 11 that expresses the electromagnetic attractive force F4 in the second gap gp2 (the coil below the mover core 20). It can be mentioned that the electromagnetic attractive force F3 acting on the first gap gp1 is set stronger than the electromagnetic attractive force F4 acting on the second gap gp2 by increasing the number of turns in 11).

  In addition, for example, a direct current component (offset current) is superimposed on the current flowing in the coil 11 (the coil 11 above the mover core 20) that causes the electromagnetic attractive force F3 to appear in the first gap gp, so that the first gap The energization amount of the coil 11 (the coil 11 above the mover core 20) that causes the electromagnetic attraction force F3 to develop in gp1, and the coil 11 (the lower part of the mover core 20 that causes the electromagnetic attraction force F4 to appear in the second gap gp2). The electromagnetic attraction force F3 acting on the first gap gp1 is set to be stronger than the electromagnetic attraction force F4 acting on the second gap gp2. In addition, the electromagnetic attractive force F3 · generated in the first gap gp1 and the second gap gp2 can also be obtained by making the gap dimension (interval) between the first gap gp1 and the second gap gp2 unbalanced. It is possible to set a difference in the strength of F4.

  In addition, in this embodiment, the element member which comprises the mover 2 among the component parts which comprise the magnetic circuit mc by attaching the permanent magnet 12 which makes a pair to the stator side opposing part 10b * 10b of the stator core 10 is provided. This is a movable core type actuator which is only a mover core 20 also called an iron core, but as shown in FIG. 6, permanent magnets 112a and 112b (112c and 112d) paired with the mover side facing portion 120b of the mover 102. Can be applied to a movable magnet type actuator in which a permanent magnet 112 is included in an element member constituting the mover 102, and various modifications can be made without departing from the spirit of the present invention. In FIG. 6, reference numeral 101 denotes a stator, reference numeral 110 denotes a stator core, and reference numeral 120 denotes a mover core.

DESCRIPTION OF SYMBOLS 10 ... Stator core 10b ... Stator side facing part 11 ... Coils 12, 12a, 12b, 12c, 12d ... Permanent magnet 2 ... Movable element 2b ... Support base end 20b ... Movable element side facing part 3 ... Electromagnetic support part gp1 ... 1st gap gp2 ... 2nd gap F3, F4 ... Electromagnetic attractive force (F3-F4) ... Energizing force

Claims (2)

A first gap and a second gap are provided between a mover that is cantilevered at the support base end so as to be movable along a predetermined reciprocating direction, and a portion of the mover that is displaced from the support base end. A stator core having a pair of stator-side facing portions to be formed, a coil wound around the stator core, and a mover-side facing portion or stator core facing the stator-side facing portion of the mover A pair of permanent magnets arranged in the reciprocating direction on one side of the stator side facing portion and having a pair of reversed magnetic poles on the side facing the facing portion on the other side, and by energizing the coil It is configured to reciprocate the mover by weakening the magnetic flux generated by the magnet located in the required direction among the permanent magnets paired with the generated magnetic flux, and strengthening the magnetic flux generated by the other magnet,
Each electromagnetic attraction is set with a difference in the strength of the electromagnetic attraction force that pulls the mover in the opposite direction, which is expressed in the first gap and the second gap, respectively, by energization of the coil or magnetic flux generated by the permanent magnet. A linear actuator comprising an electromagnetic support portion that electromagnetically supports a portion of a mover displaced from a support base end by an urging force obtained by a difference in force. Of the electromagnetic attractive forces acting on the first gap and the second gap, one electromagnetic attractive force that pulls the mover toward the anti-gravity direction side and the other electromagnetic force that pulls the mover toward the gravity direction side. The linear actuator according to claim 1, wherein the linear actuator is set stronger than the suction force.

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