JP5527066B2 - Moving magnet type linear actuator - Google Patents

Description

  The present invention relates to a movable magnet type linear actuator that reciprocates a mover using magnetic flux generated by a permanent magnet, and more particularly to a movable magnet type linear actuator in which adjustment of magnetic flux distribution is optimized.

  The movable magnet type linear actuator mainly includes a magnetic circuit that reciprocally moves the movable element relative to the stator when energized, as exemplified in Patent Document 1. The magnetic circuit is arranged along the reciprocation direction in a stator core that constitutes a stator, a mover core that constitutes a mover, and an opposing portion of the mover core that faces the stator core. The permanent magnet is configured to include a pair of permanent magnets having a reversed magnetic pole on the side facing the child core and a coil wound around the stator core, and the magnetic flux generated by energizing the coil forms a pair. The mover is reciprocated relative to the stator core by weakening the magnetic flux generated by a magnet located in a required direction among the magnets and strengthening the magnetic flux generated by the other magnet.

JP 2001-330329 A

  The magnetic flux generated between the mover core and the stator core by the permanent magnet determines the actuator specifications such as the operation characteristics of the mover driven by energizing the coil as described above. It is desirable that the magnetic flux distribution can be adjusted so that the operation characteristics according to the application can be obtained.

  However, although it is conceivable to change the magnetic flux distribution by changing the thickness or material of the permanent magnet, the use of multiple types of permanent magnets increases the number of parts used and increases the cost required for the permanent magnet. Manufacturing cost will increase. In addition, since there are restrictions on the thickness and material of the permanent magnet, it is difficult to finely adjust the magnetic flux distribution.

  The present invention has been made paying attention to such a problem, and an object thereof is to provide a movable magnet type linear actuator capable of appropriately adjusting the magnetic flux distribution of a permanent magnet without increasing the manufacturing cost. That is.

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

  In other words, the movable magnet type linear actuator of the present invention is a linear actuator that reciprocally moves the mover relative to the stator, and includes a stator core that constitutes the stator, and a mover core that constitutes the mover. A pair of permanent magnets arranged in a reciprocating direction in a facing portion of the mover core facing the stator core and having reversed magnetic poles on the side facing the stator core, and the fixed A magnetic circuit including a coil wound around the child core, and a magnetic flux generated by energizing the coil weakens a magnetic flux generated by a magnet located in a required direction among the pair of permanent magnets, The mover is reciprocated by strengthening the magnetic flux generated by the magnet, and a part of the facing part is notched between the part of the facing part of the mover core that is the magnetic flux path and the permanent magnet. West Characterized in that it constitutes a magnetic flux distribution adjusting section that changes as compared with the case without the magnetic flux distribution of the permanent magnets is the gap portion by forming a low air gap magnetic permeability than the armature core.

  In this way, it is possible to adjust the magnetic flux distribution of the permanent magnet to a desired magnetic flux distribution simply by forming a gap with the opposed portion of the mover core constituting the mover being cut away. Compared to the case of using multiple types of permanent magnets, the magnetic flux distribution can be adjusted to achieve the desired operating characteristics without increasing the manufacturing cost, and the magnetic flux distribution can be adjusted according to the installation state such as the orientation of the device. It becomes possible to do. In addition, since the gap is formed by cutting away the facing part of the mover core that constitutes the mover, there is no need to add new parts or drastically change the manufacturing process, reducing the manufacturing cost. It becomes possible to pursue.

  In order to appropriately adjust the offset position, which is a balance point between the gravity acting on the mover and the offset force due to the magnetic flux of the permanent magnet, without increasing the manufacturing cost and increasing the size of the apparatus, the magnetic circuit is: An offset force is applied to the mover by the magnetic flux generated by the permanent magnet in a state where the coil is not energized, and the magnetic flux distribution adjusting unit causes the gravity acting on the mover and the offset force by the permanent magnet to It is preferable that the offset position, which is a balance point, is changed as compared with the case where there is no gap.

  In order to change the offset position, which is a balance point between the gravity acting on the mover and the offset force due to the magnetic flux of the permanent magnet, in the anti-gravity direction, the permanent magnet on the gravity direction side of the pair of permanent magnets is opposed. It is desirable that the gap is formed only in the facing portion.

  In order to realize a new aspect of the magnetic spring characteristic, which is the relationship between the relative position of the mover with respect to the stator core and the spring force of the magnetic spring, the magnetic circuit is permanent when the coil is energized. The spring force of the magnetic spring that changes in accordance with the relative position of the mover with respect to the stator core due to the magnetic flux generated by the magnet is superimposed on the electromagnetic driving force generated by energization of the coil and acts on the mover. It is preferable that the magnetic spring characteristic, which is the relationship between the relative position of the mover with respect to the stator core and the spring force of the magnetic spring, is changed by the distribution adjusting unit as compared with the case where there is no gap.

  In order to improve control accuracy and efficiency when an actuator is used as a control element, both ends of the opposing portion in the axial center direction that is the same as the movable direction of the mover are left, and a portion sandwiched between both ends is cut. It is effective to be formed in a lacking state.

  In order to make it possible to adjust the magnetic flux distribution even when a plurality of pairs of permanent magnets are used in order to increase the electromagnetic driving force that reciprocates the mover by energization, the permanent magnets must have multiple pairs. In addition, it is mentioned that the gap is formed between at least one of the permanent magnets in each pair and the facing portion facing the permanent magnet.

  As described above, the present invention makes it possible to adjust the magnetic flux distribution simply by forming a gap with the opposed portion of the stator core notched, compared with the case of using a plurality of types of permanent magnets. Without increasing the manufacturing cost, it is possible to adjust the magnetic flux distribution so as to obtain desired operating characteristics, and to adjust the magnetic flux distribution according to the mounting state such as the orientation of the apparatus. In addition, since the gap is formed by cutting away the facing part of the fixed core, it is possible to pursue a reduction in manufacturing costs without the need for new parts or significant changes in the manufacturing process. Become. Therefore, it is possible to provide a movable magnet type linear actuator suitable for reducing manufacturing costs, improving control accuracy, and increasing efficiency.

The cross-sectional view which shows typically the movable magnet type linear actuator which concerns on one Embodiment of this invention. The AA longitudinal cross-sectional view of the movable magnet type linear actuator shown in FIG. Explanatory drawing regarding the operation | movement which reciprocates a needle | mover by the electricity supply to a coil. Explanatory drawing regarding the thrust (The spring force of a magnetic spring, offset force) which arises in the needle | mover by the magnetic flux of a permanent magnet. Explanatory drawing which shows the relationship between the relative position of the needle | mover with respect to a stator core, and the thrust (The spring force of a magnetic spring, offset force) which arises in a needle | mover with the magnetic flux of a permanent magnet. Explanatory drawing which compares and shows the case where a space | gap part is formed about an offset position, and the case where there is no space | gap part. Comparison of the relationship between the relative position of the mover relative to the stator core and the thrust (magnetic spring force, offset force) generated in the mover by the magnetic flux of the permanent magnet, when the gap is formed and when there is no gap FIG. The longitudinal section of the movable magnet type linear actuator concerning other embodiments of the present invention. In the embodiment shown in FIG. 8, when the gap is formed with respect to the relationship between the relative position of the mover with respect to the stator core and the thrust (magnetic spring spring force, offset force) generated in the mover by the magnetic flux of the permanent magnet, Explanatory drawing which compares and shows the case where there is no part. The longitudinal cross-sectional view of the movable magnet type linear actuator which concerns on embodiment other than the above of this invention. In the embodiment shown in FIG. 10, when the gap is formed with respect to the relationship between the relative position of the mover with respect to the stator core and the thrust (magnetic spring spring force, offset force) generated in the mover by the magnetic flux of the permanent magnet, Explanatory drawing which compares and shows the case where there is no part. The longitudinal cross-sectional view of the movable magnet type linear actuator which concerns on embodiment other than the above of this invention. The longitudinal cross-sectional view of the movable magnet type linear actuator which concerns on embodiment other than the above of this invention.

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

  The movable magnet type linear actuator of the present embodiment is an inner rotor type linear actuator in which the movable element 2 is arranged on the radially inner side of the stator 1, as shown in FIGS. 1 and 2, and is fixed in a substantially cylindrical shape. A child 1; a mover 2 which is disposed radially inside the stator 1 and can reciprocate along an axial direction (reciprocating direction); and a magnetic circuit mc for reciprocating the mover 2. ing. The radially outer side refers to the direction away from the axis, and the radially inner side refers to the direction approaching the axis. As shown in the figure, the shape of the mover or stator is a cylinder or cylinder. It is not meant to be limited to.

  The stator 1 is substantially cylindrical and has a stator core 10 formed with a pair of salient pole portions 10b and 10b extending radially inward from the inner wall 10a, and wound around the salient pole portions 10b and 10b. And a coil 11 to be operated. The stator core 10 is configured by stacking and fixing a plurality of stator core plates (not shown) along the axial direction.

  The mover 2 includes a substantially rod-shaped mover core 20 disposed between the salient pole portions 10b and 10b of the stator core 10, and the salient pole portions 10b and 10b of the stator core 10 of the mover core 20. And a pair of permanent magnets 12 (12a and 12b) arranged in the axial direction (reciprocating direction) on a facing portion 20a (facing surface). The permanent magnets 12a and 12b forming a pair are arranged with the magnetic poles of the surfaces facing the stator cores 10 reversed. Similar to the stator core 10 constituting the stator 1, the mover core 20 is configured by stacking and fixing a plurality of unillustrated mover core plates along the axial direction. Further, the movable element 2 is capable of reciprocating along the axial direction by supporting both sides in the axial direction with mechanical springs such as a leaf spring (not shown).

  The magnetic circuit mc includes the mover core 20, the stator core 10, a pair of permanent magnets 12 (12 a and 12 b), and the coil 11. When the coil 11 is energized, The mover 2 is reciprocated. In the present embodiment, the movable magnet type (moving magnet type) actuator is configured with the permanent magnet 12 and the movable core 20 as the component parts constituting the mover 2 among the plurality of element parts constituting the magnetic circuit mc. . Specifically, when the coil 11 is not energized, as shown in FIG. 3 (a), magnetic fluxes mf1 · which are different in direction from each other on both sides in the reciprocating direction of the mover 2 by the pair of permanent magnets 12a · 12b. mf2 is expressed. In this case, when the coil 11 is energized in the positive direction, a magnetic flux mf is generated by energizing the coil 11 as shown in FIGS. 1 and 3B, and the two magnetic fluxes mf1 and mf2 generated by the permanent magnet 12 are generated. Among them, the magnetic flux mf1 in the same direction as the magnetic flux mf by the coil 11 is strengthened, the other magnetic flux mf2 is weakened, and the electromagnetic driving force F1 acts so that the strong magnetic flux side of the mover 2 approaches the stator core 10, thereby moving the mover 2 Move in the X1 direction. On the other hand, when the coil 11 is energized in the reverse direction, as shown in FIG. 3C, the electromagnetic driving force F2 acts to move the mover 2 in the X1 direction, which is the reverse direction of the X2 direction. That is, the magnetic circuit mc weakens the magnetic flux mf2 (mf1) generated by the magnet 12a (12b) positioned in a required direction among the permanent magnets 12a and 12b paired with the magnetic flux mf generated by energizing the coil 11, and the other By increasing the magnetic flux mf1 generated by the magnet 12b (12a), an electromagnetic driving force F1 (F2) is applied to the mover 2 to reciprocate the mover 2.

  Further, the magnetic circuit mc applies a thrust to the mover 2 by the magnetic flux generated by the permanent magnet 12. That is, when the mover 2 is located at a position ps1 where the magnetic flux densities on both sides in the reciprocating direction of the mover 2 are equal, as schematically shown in FIG. For example, as the mover 2 is displaced in the X1 direction, the magnetic flux path on the X2 direction side becomes wider and the magnetic flux path on the X1 direction side becomes narrower, so that the magnetic flux density on the X2 direction side becomes weaker. The magnetic flux density on the X1 direction side becomes stronger. In this case, thrust F3 acts on the mover 2 so as to move to the position ps1 where the magnetic flux densities on both sides of the reciprocating direction of the mover 2 become equal. As shown in FIG. 5, the thrust F3 changes in magnitude and direction according to the relative position of the mover 2 with respect to the stator core 10 (the amount of displacement from the center of the movable range of the mover). It is called the spring force of the spring, and when the mover 2 is displaced from a predetermined position (displacement amount 0), it acts to return the mover 2 to a predetermined position (displacement amount 0). Called. This thrust F3 (spring force or offset force of the magnetic spring) is determined by the magnetic flux density, magnetic flux distribution, magnetic pole pitch between the mover core 20 and the permanent magnet 12, etc. In this embodiment, the mover 2 is movable. It is set to increase as the mover 2 moves away from the center of the range (the amount of displacement is 0). Of course, the thrust F3 may be set to be constant regardless of the displacement of the mover 2. The thrust F3 generated by the permanent magnet 12 is superimposed on the magnetic driving forces F1 and F2 generated by energizing the coil 11 as the spring force of the magnetic spring when the coil 11 is energized. When the coil 11 is not energized, it acts on the mover 2 as an offset force.

  However, as shown in FIG. 5, in the case where the offset force due to the magnetic flux of the permanent magnet 12 is set so as to return the mover 2 to the center of the movable range of the mover 2 in the horizontal state where the reciprocating direction is horizontal, As shown in FIGS. 6A and 5, when the linear actuator is placed in a vertical state in which the reciprocating direction intersects the horizontal direction, the offset force (thrust force) at the center ps2 (displacement amount 0) of the movable range of the movable element 2 is obtained. 0) is defeated by the gravity mg acting on the movable element 2, and the movable element 2 is shifted by a distance D1 downward from the center ps2 of the movable range to the offset position ps4 which is a balance point between the gravity mg and the offset force F4. 2 goes down. In this case, in order to avoid a collision with a casing (not shown) that houses the mover 2 and the stator 1, the reciprocable range of the mover 2 is narrower than the original movable range, and the reciprocable range is smaller than the reciprocable range. However, there is a problem that the movable element 2 cannot be reciprocated with an amplitude that requires a wide range.

  In addition, the magnetic flux generated between the mover 2 and the stator core 10 by the permanent magnet 12 is not only the offset force described above, but also the spring force of the magnetic spring and the relative position of the mover 2 with respect to the stator core 10. Since the specifications of the actuator, such as the magnetic spring characteristics and the operating characteristics of the mover, which are related to each other, are determined, it is desirable that the magnetic flux distribution can be adjusted according to the purpose and application in order to solve the above problems. However, changing the magnetic flux distribution by changing the thickness, material, etc. of the permanent magnet is considered as one means. However, the use of multiple types of permanent magnets increases the number of parts used and the cost required for the permanent magnets. This increases the manufacturing cost. Moreover, since the thickness and material of the permanent magnet are limited, it is difficult to finely adjust the magnetic flux distribution.

  Therefore, in this embodiment, as shown in FIGS. 1 and 2, a part of the facing portion 20 a is notched between the part of the facing portion 20 a of the mover core 20 that is a magnetic flux path and the permanent magnet 12. In this state, the magnetic flux distribution of the permanent magnet 12 is changed as compared with the case where there is no air gap 30 by forming the air gap 30 having a magnetic permeability lower than that of the mover core 20. This gap portion 30 leaves the opposite ends 20a in the axial direction both ends 20b and 20b, which are the same as the moving direction of the mover 2, and cuts out the portions sandwiched between both ends 20b and 20b. Of the permanent magnets 12a and 12b formed, the permanent magnets 12a and 12b are formed only on the facing portion 20a facing the permanent magnet 12b on the gravity direction side. The depth between the facing portion 20a where the gap 30 is formed and the permanent magnet 12b is set to be constant. Both end portions 20b and 20b are in contact with a pair of permanent magnets 12a and 12b, respectively. The permanent magnet 12b in which the gap portion 30 is formed between the opposed portion 20a of the movable piece core 20 constituting the movable piece 2 has a weaker mounting strength with respect to the movable piece core 20, but both end portions 20b of the opposed portion 20a. The end portion 20b (20c) on the gravity direction side of 20b also serves as a column portion that supports the permanent magnet 12b.

  When such a gap portion 30 is formed, the both end portions 20b and 20b on both sides in the axial direction have higher magnetic permeability than the gap portion 30 on the center side in the axial center direction, and a magnetic flux is applied to both end portions 20b and 20b. As a result, the magnetic flux at both ends in the axial direction becomes stronger, and the magnetic flux at the center in the axial direction sandwiched between both ends 20b and 20b becomes weaker. This magnetic flux distribution reduces the force with which the mover 2 stays in the axial direction (reciprocating direction) center side, so that the amount of change in the spring force of the magnetic spring with respect to the movable range of the mover 2 as shown in FIG. (Gradient) decreases from gr2 to gr1.

  Further, as shown in FIG. 2, the gap 30 is formed only in the facing portion 20a facing the permanent magnet 12b of the paired permanent magnets 12a and 12b. The magnetic flux on the gravity direction side is strengthened to cause an unbalanced state of the magnetic flux, and as shown in FIG. 7, the offset force due to the magnetic flux of the permanent magnet 12 increases in the direction toward the antigravity direction where the magnetic flux is strong. As shown in FIGS. 6 and 7, when there is no gap 30, the offset position, which is a balance point between the gravity mg acting on the mover 2 and the offset force F <b> 4 by the permanent magnet 12, is Although the position ps4 is shifted by a distance D1 downward from the center ps2 of the movable range, the offset position is changed to the center ps2 of the movable range of the mover 2 by forming the gap 30.

  Thus, the magnetic flux distribution adjustment part 3 which changes the magnetic flux distribution of the permanent magnet 12 compared with the case where there is no air gap part 30 by forming the air gap part 30 is configured. The offset position, which is a balance point between the gravity mg acting on and the offset force F4 by the permanent magnet 12, is changed from the position ps4 when there is no gap 30 to the position ps2 (see FIG. 6). In addition, as shown in FIG. 7, the magnetic flux distribution adjusting unit 3 has a magnetic spring characteristic, which is a relationship between the relative position of the mover 2 with respect to the stator core 10 and the spring force of the magnetic spring, when there is no gap 30. Compared to change. These offset force F4 and magnetic spring characteristics can be adjusted by variously changing the dimension of the gap 30 in the axial direction, the dimension perpendicular to the axial direction, the shape such as the depth, the arrangement position, the number of formed elements, etc. It is. For example, it may be formed such that the bottom surface of the gap portion 30 is inclined with respect to the axis, or formed so that the size and depth of the gap portion 30 change along the axis.

  As described above, the movable magnet type linear actuator of the present embodiment is a movable magnet type linear actuator that reciprocates the mover 2 relative to the stator 1, and includes a stator core 10 that constitutes the stator 1, and a movable The magnetic poles on the side facing the respective stator cores 10 are arranged along the reciprocating direction in the mover core 20 constituting the child 2 and the facing portion 20a of the mover core 20 facing the stator core 10. A magnetic circuit mc that includes a permanent magnet 12 (12a, 12b) that forms an inverted pair and coils 11 and 11 that are wound around the stator core 10, and a magnetic flux that is generated by energizing the coil 11 The magnetic flux mf2 (mf1) generated by the magnet 12a (12b) located in the required direction among the permanent magnets 12a and 12b with which mf is paired is weakened, and the magnetic flux mf1 generated by the other magnet 12b (12a) The armature 2 is reciprocated by strengthening mf2), and a part of the facing portion 20a is notched between the portion of the facing portion 20a of the armature core 20 that is a magnetic flux path and the permanent magnet 12. In this state, the magnetic flux distribution adjusting unit 3 is configured to change the magnetic flux distribution of the permanent magnet 12 as compared with the case where there is no air gap 30 by forming the air gap 30 having a lower magnetic permeability than that of the mover core 20. Yes.

  As described above, the magnetic flux distribution of the permanent magnet 12 is adjusted to a desired magnetic flux distribution simply by forming the gap 30 with the opposed portion 20a of the movable core 20 constituting the mover 2 cut out. Because it is possible, it is possible to adjust the magnetic flux distribution to achieve the desired operating characteristics without increasing the manufacturing cost compared to the case of using multiple types of permanent magnets, and according to the mounting state such as the orientation of the device. Thus, the magnetic flux distribution can be adjusted. Moreover, since the gap 30 is only formed by cutting away the facing portion 20a of the mover core 20 constituting the mover, no additional parts or significant changes in the manufacturing process are required, and the manufacturing cost is reduced. Can be reduced.

  In order to adjust the offset position of the mover 2, in addition to changing the permanent magnet 12 described above, it may be possible to provide another mechanism such as a leaf spring. In addition to an increase in manufacturing cost, there is a problem that the actuator itself becomes large. On the other hand, in the present embodiment, the magnetic circuit mc applies the offset force F4 to the mover 2 by the magnetic flux generated in the permanent magnet 12 when the coil 11 is not energized, and the magnetic flux distribution adjusting unit 3, the offset position, which is a balance point between the gravity mg acting on the mover 2 and the offset force F <b> 4 by the permanent magnet 12, is changed as compared with the case where there is no gap 30. As described above, the offset position can be adjusted to a desired position simply by forming the gap portion 30, and the manufacturing cost is increased and the apparatus is increased as compared with the case where a plurality of types of permanent magnets are used or other mechanisms are introduced. Thus, the offset position can be adjusted appropriately without increasing the size.

  In particular, in the present embodiment, since the gap 30 is formed so that the offset position is the center ps2 of the movable range of the movable element 2, the amplitude of the reciprocating operation of the movable element 2 is maximized, It is possible to effectively use the movable range.

  Furthermore, in this embodiment, since the air gap 30 is formed only in the facing portion 20a that faces the permanent magnet 12b on the gravitational direction side among the pair of permanent magnets 12a and 12b, the magnetic flux on the gravitational direction side is formed into the air gap. 30, the magnetic flux on the antigravity direction side becomes strong and an unbalanced state of the magnetic flux occurs, and the offset force due to the magnetic flux of the permanent magnet 12 increases in the direction toward the antigravity direction where the magnetic flux is strong. It is possible to change the offset position, which is a balance point between the acting gravity mg and the offset force F4 by the permanent magnet 12, to the anti-gravity direction side.

  Alternatively, in the conventional movable magnet type linear actuator, it is difficult to design by changing the magnetic flux distribution of the permanent magnet to adjust the magnetic spring characteristics, and there are the following problems. That is, when a movable magnet type linear actuator is used as a power source for a piston pump or the like, although it is generally reciprocated in a highly efficient resonance state, a load is applied to a mechanical spring such as a leaf spring, and the mechanical spring There is a problem that the life of the product is reduced. In addition, in order to obtain the spring constant necessary for the resonance motion, the magnetic spring cannot be adjusted and is fixed, so it is necessary to cope with only the mechanical spring, which increases the cost required for the mechanical spring. In addition, when a movable magnet type linear actuator is used as a control element for position control, force control, etc. of a positioning device, vibration device, linear servo motor, etc., the spring force of the magnetic spring is a cause of control obstruction and thrust loss. Become. In addition to the above, in order to realize a new aspect of the spring characteristics such as reducing or eliminating the spring constant of the mechanical spring and the magnetic spring, for example, in addition to the mechanical spring characteristics, the degree of freedom in designing the magnetic spring characteristics However, since it is difficult to adjust the magnetic spring characteristics as described above, it is difficult to realize this.

  In contrast to such a conventional movable magnet type linear actuator, in the present embodiment, the magnetic circuit mc has the movable element 2 for the stator core 10 by the magnetic flux generated by the permanent magnet 12 when the coil 11 is energized. The spring force of the magnetic spring that changes according to the relative position of the magnetic spring acts on the mover 2 by superimposing on the electromagnetic driving force F1 (F2) generated by energizing the coil 11, and is fixed by the magnetic flux distribution adjusting unit 3. The magnetic spring characteristic, which is the relationship between the relative position of the mover 2 relative to the child core 10 and the spring force of the magnetic spring, is changed as compared with the case where there is no gap 30. In this way, the relationship between the relative position of the mover 2 with respect to the stator core 10 and the spring force of the magnetic spring is obtained simply by forming the gap 30 with the facing portion 20a of the mover core 20 cut away. Since the magnetic spring characteristic can be adjusted to a desired characteristic, when the actuator is used as a power source, the magnetic spring characteristic is adjusted so that the load on the mechanical spring is distributed to the magnetic spring. In addition to improving the life of the magnetic spring, it is possible to reduce the cost required for the mechanical spring by using both the magnetic spring and the mechanical spring in obtaining the spring constant necessary for the resonance motion. Furthermore, when an actuator is used as a control element, the magnetic spring characteristics are adjusted so that the spring force of the magnetic spring is reduced, and the spring force of the magnetic spring may cause a hindrance to control and a thrust loss. It becomes possible to reduce and improve control accuracy and efficiency. In addition, since the magnetic spring characteristic can be adjusted by the magnetic spring adjustment unit, it is possible to realize a new aspect of the spring characteristic such as reducing or eliminating the spring constant of the mechanical spring and the magnetic spring.

  Further, in the present embodiment, the opposing portion 20a is formed by leaving the both ends 20b and 20b in the axial direction that is the same as the moving direction of the mover 2 and notching the portions sandwiched between the both ends 20b and 20b. Therefore, both ends 20b and 20b on both sides in the axial direction have higher magnetic permeability than the gap 30 on the center side in the axial direction, and magnetic flux concentrates on both ends 20b and 20b. The magnetic flux at both ends in the axial direction becomes stronger, the magnetic flux at the central side in the axial direction sandwiched between both ends 20b and 20b becomes weaker, and the force that the mover tries to stay on the central side in the axial direction (reciprocating direction) Therefore, the amount of change in the spring force of the magnetic spring with respect to the movable range of the mover 2 (inclination shown in FIG. 7) is reduced from gr2 to gr1, thereby facilitating movement control of the mover and improving control accuracy. it can. In addition, since the spring force of the magnetic spring is reduced, the thrust loss caused by the spring force of the magnetic spring is reduced, and the efficiency can be improved.

  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, what is shown in FIG. 8 is mentioned as other embodiment which concerns on this invention. That is, the air gap 130 is formed only in the facing portion 120a that faces the permanent magnet 12b on the gravity direction side of the pair of permanent magnets 12a and 12b, and the space between the permanent magnet 12b on the gravity direction side and the mover core 120 faces. The depth between the permanent magnet 12b and the facing portion 120a is set to be constant over the entire axial direction so that the contact with the portion 120a is eliminated. In this way, when the facing portion 120a that forms the contact 120b with the permanent magnet 12 is formed only on one side in the axial direction of the gap portion 130, as shown in FIG. In a state where the change amount (gradient) of (the spring force and offset force of the magnetic spring) is maintained, the thrust by the magnetic flux of the permanent magnet 12 (the spring force and offset force of the magnetic spring) is in the direction toward the antigravity direction where the magnetic flux is strong. growing.

  Furthermore, what is shown in FIG. 10 is mentioned as embodiment other than the above of this invention. That is, the gap portion 230 is formed in a state in which both ends 220b and 220b in the axial center direction, which is the same as the moving direction of the mover 202, are left out of the facing portion 220a, and the portions sandwiched between the both ends 220b and 220b are cut out. Thus, the depth between the permanent magnets 12a and 12b and the facing portion 220a is set to be constant. Both end portions 220b and 220b are in contact with a pair of permanent magnets 12a and 12b, respectively. The boundary line between the pair of permanent magnets 12a and 12b is the center of the movable range of the mover, and the gap 230 is formed so as to be symmetric about the boundary line between the pair of permanent magnets 12a and 12b. Yes. In this manner, both end portions 220b and 220b of the facing portion 220a that are contact points with the permanent magnet 12 are formed on both sides in the axial direction of the gap portion 230, and the boundary line between the permanent magnets 12a and 12b that the gap portion 230 forms a pair. Since it is formed so as to be symmetrical with respect to the center, as shown in FIG. 11, the amount of change (gradient) of the thrust (spring force of the magnetic spring, offset force) with respect to the movable range of the movable element 202 is the movable of the movable element. It reduces over the whole movable range of the needle | mover 202 in the state which maintained the thrust in the center of the range.

  In addition, as shown in FIG. 12, the mover core 320 constituting the mover 302, the opposed portion 320a of the stator core 310 and the pair of permanent magnets 12a and 12b are made into one unit, and one unit is an axial center. A plurality of permanent magnets 12a and 12b are provided along the direction so as to form a plurality of pairs, and at least one of the permanent magnets 12a and 12b constituting each unit and the permanent magnet 12b. It is mentioned that the space | gap part 330 is formed between the opposing parts 320a which are facing. With this configuration, the magnetic flux distribution of the permanent magnet 12 is adjusted even when a plurality of pairs of permanent magnets 12a and 12b are used to increase the electromagnetic driving force that reciprocates the mover 302 by energization. Thus, it becomes possible to adjust the thrust (spring force or offset force of the magnetic spring) acting on the mover 302 by the magnetic flux of the permanent magnet 12. Of course, the effect obtained by forming the gap portion 330 is similar to the shape and arrangement position of the gap portion described in the above embodiment.

  Further, as shown in FIG. 13, the coil 11 is not wound around each of the salient pole portions 410b with respect to the stator core 410 having the plurality of salient pole portions 410b, and the plurality of salient pole portions 410b are integrated into the coil. 11 may be wound.

  Further, a mechanical spring portion such as a leaf spring (not shown) that supports the above-described movable element 2 so as to be able to reciprocate causes the urging force that changes depending on the relative position of the movable element 2 to the stator core 10 to act on the movable element 2. In the movable range of the movable element 2, there is a configuration in which the gap is formed so that the spring force of the magnetic spring acts in the opposite direction to the direction in which the urging force of the mechanical spring acts. When configured in this way, the urging force of the mechanical spring is weakened or canceled by the spring force of the magnetic spring, and the movable magnet type linear actuator having a new spring characteristic in which the spring constant of the mechanical spring and the magnetic spring is reduced or eliminated. Can be provided.

  In addition, in the present embodiment, the inner rotor type linear actuator is described as an example. However, of course, the outer rotor type linear actuator in which the movable element 2 is arranged radially outside the stator 1 with the axis at the center. It is also applicable to.

  In addition, various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Stator 11 ... Coil 10,110,210,310 ... Stator core 12a * 12b ... Permanent magnet 12b which makes a pair ... Permanent magnet 2,102,202,302 ... Gravity direction lower side Mover 20,120, 220, 320 ... mover cores 20a, 120a, 220a, 320a ... opposing portions 20b, 20b, 220b, 220b ... both ends 3 ... magnetic flux distribution adjusting parts 30, 130, 230, 330 ... gap part mc ... magnetic circuit mf ... coil Magnetic fluxes mf1, mf2 generated by energization: Magnetic flux F4 by permanent magnets ... Offset force

Claims (6)

A movable magnet type linear actuator that reciprocally moves the mover relative to the stator,
A stator core that constitutes the stator, a mover core that constitutes the mover, and a stator that is arranged along a reciprocating direction in an opposing portion of the mover core that faces the stator core. Comprising a magnetic circuit comprising a pair of permanent magnets having reversed magnetic poles on the side facing the core and a coil wound around the stator core;
The magnetic flux generated by energizing the coil weakens the magnetic flux generated by the magnet located in the required direction among the paired permanent magnets, and reciprocates the mover by strengthening the magnetic flux generated by the other magnet,
By forming a gap with a lower permeability than the mover core between the part of the facing part of the mover core that is the magnetic flux path and the permanent magnet, with the part of the facing part notched. A movable magnet type linear actuator comprising a magnetic flux distribution adjusting unit for changing a magnetic flux distribution of a permanent magnet as compared with a case where there is no gap. The magnetic circuit applies an offset force to the mover by a magnetic flux generated by a permanent magnet in a state where current is not supplied to the coil,
2. The movable according to claim 1, wherein the magnetic flux distribution adjusting unit changes an offset position, which is a balance point between gravity acting on the movable element and an offset force by the permanent magnet, as compared with the case where there is no gap. Magnet type linear actuator.   3. The movable magnet type linear actuator according to claim 1, wherein the gap is formed only in a facing portion of the pair of permanent magnets that faces a permanent magnet on the gravity direction side. The magnetic circuit is an electromagnetic drive in which a spring force of a magnetic spring that changes according to the relative position of the mover with respect to the stator core is generated by energizing the coil due to the magnetic flux generated by the permanent magnet when the coil is energized. Acting on the mover superimposed on the force,
4. The magnetic spring characteristic, which is a relationship between the relative position of the mover relative to the stator core and the spring force of the magnetic spring, is changed by the magnetic flux distribution adjusting unit as compared with the case where there is no gap. A movable magnet type linear actuator according to claim 1.   5. The gap portion is formed in a state in which both ends of the opposing portion in the axial center direction that is the same as the movable direction of the mover are left and portions sandwiched between the both ends are cut out. The movable magnet type linear actuator according to any one of the above. The said permanent magnet has comprised multiple pairs, The said space | gap part is formed between at least one permanent magnet among the permanent magnets which make each pair, and the opposing part facing the said permanent magnet. The movable magnet type linear actuator in any one of 1-5.

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