JP5258234B2 - Linear motor actuator - Google Patents

Description

  The present invention relates to a linear actuator in which a guide shaft and a slide member are relatively movable in accordance with an input signal, and in particular, a linear motor is used as a drive means for relatively moving the guide shaft and the slide member. It relates to the adopted linear motor actuator.

  Conventionally, as this type of linear motor actuator, one disclosed in WO2007 / 026673A1 is known. This linear motor actuator is a combination of a rod-type linear motor as a thrust generation source and a ball spline device as a linear guide means, and the magnet rod that constitutes the linear motor is the interior of the spline shaft that constitutes the ball spilan. Stored in Specifically, a spline shaft that has a hollow portion and is formed in a cylindrical shape and has slit openings along the longitudinal direction, and the spline shaft that is assembled to the spline shaft via a large number of balls. A spline nut that guides the shaft in the axial direction, a magnet rod supported at both ends in the hollow portion of the spline shaft, and a linear motor that is disposed in the hollow portion of the spline shaft and is coupled with the magnet rod, the slit And a forcer coupled with the spline nut through an opening.

  The forcer incorporates a coil member, and when a drive current is passed through the coil member, the forcer is propelled in the axial direction in the hollow portion of the spline shaft along the magnet rod. As a result, the spline nut coupled to the forcer through the slit opening of the spline shaft is propelled in the axial direction outside the spline shaft, and the spline nut is moved to an arbitrary amount with respect to the spline shaft in response to energization of the drive current. It is possible to move with.

The conventional linear motor actuator configured as described above has a rod type linear motor as a thrust generation source and a ball spline device as a linear guide means as a result of storing the rod type linear motor in the hollow portion of the spline shaft. It is fused in a compact manner, making it very easy to handle.
WO2007 / 026673A1

  However, in the conventional linear motor actuator disclosed in WO2007 / 026673A1, the forcer is formed to have a length equal to or less than the axial length of the spline nut, so that sufficient thrust is generated between the magnet rod and the forcer. Cannot be generated, and is not suitable for applications requiring a small size and high thrust.

  In addition, since the force of the linear motor generates heat when energized, it is necessary to take sufficient measures to dissipate the force of the forcer in order to prevent a reduction in thrust. However, in the conventional linear motor actuator, the forcer is covered with a spline nut. For this reason, there has been a concern that the heat radiation of the forcer may not be sufficiently performed depending on the use situation such as continuous operation.

  The present invention has been made in view of such problems, and the object of the present invention is that it is possible to produce a large thrust while being able to be manufactured in a small size, and furthermore, the force of the forcer during operation. An object of the present invention is to provide a linear motor actuator capable of promoting heat dissipation.

  That is, the linear motor actuator of the present invention has a guide shaft in which the rolling surface of the rolling element is formed along the longitudinal direction, and is arranged in parallel with the guide shaft, and a plurality of magnetic poles are repeatedly arranged in the longitudinal direction. A magnetic member, a slide member that is assembled to the guide shaft via a number of rolling elements and is movable along the longitudinal direction of the guide shaft, and a linear motor together with the magnet member, and the slide The forcer is formed longer than the member in the moving direction, and the central portion in the longitudinal direction is coupled to the slide member.

  According to the linear motor actuator of the present invention configured as described above, the forcer constituting the linear motor coupled with the magnet member is formed to have a longer length in the moving direction than the slide member. Since the coil member provided in the forcer is strengthened, the thrust of the linear motor is enhanced. In addition, only the central portion in the longitudinal direction of the forcer is coupled to the slide member, and both end portions of the forcer are exposed without being covered by the slide member. For this reason, even when the forcer generates heat due to energization, cooling of the forcer can be promoted, and a reduction in the thrust of the linear motor can be prevented.

  Hereinafter, the linear motor actuator of the present invention will be described in detail with reference to the accompanying drawings.

  1 to 3 are views showing an example of a linear motor actuator to which the present invention is applied. FIG. 1 is an overall perspective view, FIG. 2 is a side view, and FIG. 3 is a center of a spline nut, which will be described later, perpendicular to the longitudinal direction. It is a cutaway perspective view. The linear motor actuator includes a spline shaft 1 having a hollow portion 10 and formed in a substantially cylindrical shape, and a spline nut 2 fitted to the outside of the spline shaft 1 through a large number of balls. The spline nut 2 and the spline shaft 1 can be relatively reciprocated in the axial direction by using a thrust generated by the linear motor 3 accommodated in the hollow portion 10 of the spline shaft 1. Yes. Here, the spline shaft 1 corresponds to a guide shaft of the present invention, and the spline nut 2 corresponds to a slide member of the present invention.

  The spline shaft 1 has a hollow portion 10 and is formed in a cylindrical shape, and two ball rolling grooves 11 are formed on the outer peripheral surface thereof with a phase difference of 180 °. The spline shaft 1 is provided with a single slit opening 12 along the axial direction at a position 90 degrees out of phase with the ball rolling groove 11. This slit opening is located below the spline shaft 1 in FIGS. Therefore, the hollow portion 10 of the spline shaft 1 described above is opened to the outside of the spline shaft 1 through the slit opening 12. Further, a flat surface 13 is formed on the outer peripheral surface of the spline shaft 1 at a position shifted in phase from the slit opening 12 by 180 °, and this flat surface 13 is a mounting surface for a linear scale described later.

  On the other hand, the spline nut 2 is formed in a substantially rectangular shape and has a through hole having an inner diameter slightly larger than that of the spline shaft 1. The spline shaft 1 is inserted into the through hole, and is assembled to the spline nut 2 via a large number of balls that roll in the ball rolling groove 11. The spline nut 2 includes a nut body 20 and a plurality of end plates 21 fixed to both end surfaces of the nut body 20 in the axial direction so as to correspond to the ball rolling grooves 11. The nut body is formed with a mounting surface 20a for a fixed portion or a movable portion of equipment using the linear actuator unit, and a tap hole 20b into which a bolt is screwed is formed on the mounting surface 20a.

  Moreover, two load rolling grooves 22 opposite to the ball rolling grooves 11 of the spline shaft 1 are formed 180 ° out of phase on the inner peripheral surface of the through hole of the nut body 20, Rolling is performed between the ball rolling groove 11 and the load rolling groove 22 while applying a load. In addition, two ball return passages 23 are formed in the nut body 20 in parallel with each load rolling groove 22, and these ball return passages 23 exist outside each load rolling groove 22. On the other hand, each end plate 21 is formed with a direction changing path for bringing the ball 3 back and forth between the load rolling groove 22 of the nut body 20 and the ball return passage 23 corresponding thereto. Are fixed to both end surfaces of the nut body 20 in the axial direction, the spline nut 2 is provided with an infinite circulation path for the balls 4. That is, in the spline nut 2 shown in FIG. 3, a pair of infinite circulation paths are formed so as to sandwich the spline shaft 1. In FIG. 3, the load rolling groove 22 and the ball return passage formed in the nut body 20 are drawn, but the ball rolling in these is not drawn.

  Accordingly, if the spline nut 2 is fixed and the spline shaft 1 is moved with respect to the spline nut, the ball 4 applies a load between the nut body 20 and the spline shaft 1 and enters the endless circulation path 25. And the spline shaft 1 can be continuously moved along the spline nut 2. Therefore, the linear motor actuator is used so that the spline nut 2 is fixed to other devices by using the tap hole 20b, and the spline shaft 1 supported by the spline nut 2 is advanced and retracted in the axial direction. Is done. On the contrary, the spline shaft 1 may be fixed to other devices, and the spline nut 2 assembled to the spline shaft 1 may be used to advance and retract in the axial direction. In an actual trial production, by using a steel ball having a diameter of 0.4 mm as the ball 4, it was possible to obtain a smooth linear reciprocating motion of the spline shaft with respect to the spline nut.

  On the other hand, a magnet rod 30 as a magnet member of the linear motor 3 is accommodated in the hollow portion 10 of the spline shaft 1. The magnet rod 30 is formed by alternately arranging N poles and S poles of permanent magnets along the axial direction, and may be manufactured by packing a large number of permanent magnets inside a steel pipe, or a molded round shape. The pole may be magnetized later to form a magnetic pole. The magnet rod 30 shown in FIG. 3 is manufactured in the former example.

  A pair of end caps 5 are fitted in openings at both axial ends of the spline shaft 1 to close the hollow portion 10 of the spline shaft 1. Holding portions for fitting the end portions of the magnet rod 30 are formed inside the end caps 5, and the magnet rod 30 is connected to the spline shaft by fixing the pair of end caps 5 to the spline shaft 1. 1 is held like a support beam at both ends, and is positioned parallel to the axial direction of the spline shaft 1. Reference numeral 51 in the figure denotes a set screw mounting hole for fixing the end cap 5 to the spline shaft 1.

  A forcer 31 that constitutes the linear motor 3 is disposed around the magnet rod 30. FIG. 4 shows details of the forcer 31. The forcer 31 includes a plurality of coil members 32 wound around the magnet rod 30 in a ring shape while maintaining a slight gap, and a resin holder 33 as an insulator that integrally holds the coil members 32. The metal reinforcing plate 34 is bonded to the resin holder 33. In addition, the code | symbol 35 in FIG. 4 is a cable for supplying a drive current to each coil member 32, and is formed from the flexible printed circuit board (FPC).

  A three-phase alternating current is applied to each coil member 32, and the coil members 32 corresponding to the U-phase, V-phase, and W-phase of the three-phase alternating current are arranged in order on the resin holder 33. Has been. In the example shown in FIG. 4, 18 coil members 32 are arranged in the resin holder 33, and six sets of three coil members 32 corresponding to the U phase, the V phase, and the W phase are arranged. Become. The arrangement pitch of the coil members 32 is set shorter than the arrangement pitch of the permanent magnets in the magnet rod 60. Magnetic flux is formed in the magnet rod 30 from the magnetic pole of S pole to the magnetic pole of N pole, and the forcer 31 incorporates a magnetic pole sensor (not shown) for detecting the magnetic flux density. Therefore, the positional relationship of each magnetic pole (N pole and S pole) of the magnet rod 30 with respect to the coil member 32 is grasped from the detection signal output from the magnetic pole sensor. The driver unit that controls the energization of the drive current to the coil member 32 receives the detection signal of the magnetic pole sensor, and calculates the phase of the optimum drive current according to the positional relationship between the coil member 32 and each magnetic pole of the magnet rod 30. Then, it energizes each coil member 32. As a result, an attractive force and a repulsive force are generated between the coil member 32 and each magnetic pole of the permanent magnet due to the interaction between the drive current flowing through each coil member 32 and the magnetic flux formed by the permanent magnet. On the other hand, the magnet rod 30 is relatively propelled in the axial direction.

  Two linear scales 14 and 15 are attached to the flat surface 13 provided on the opposite side of the spline shaft 1 from the slit opening 12 along the longitudinal direction of the spline shaft 1. The spline nut 2 is equipped with a read head 16 facing the linear scales 14 and 15 so that when the spline shaft 1 moves relative to the spline nut 2, a signal corresponding to the amount of movement is output. It is configured. The output signal of the read head 16 is transmitted to the driver unit by a cable 17. The cable 17 is formed from a flexible printed circuit board (FPC). Of the pair of linear scales 14, 15, one linear scale 14 is for detecting the position of the spline nut 2 on the spline shaft 1, and the other linear scale 15 is the home position of the spline nut 2 on the spline shaft 1. This is for returning to origin.

  As shown in the sectional view of FIG. 3, the coil member 32 of the forcer 31 surrounds the magnet rod 30 in the hollow portion of the spline shaft 1, and the resin holder 33 that holds the coil member 32 is a spline shaft. A reinforcing plate 34 protruding outside the spline shaft 1 through one slit opening 12 and bonded to the resin holder 33 is coupled to the spline nut 2 by a fixing screw. Therefore, the reinforcing plate 34 is formed with a tap hole 36 into which the fixing screw is screwed. As a result, when the magnet rod 30 is propelled relative to the forcer 31, the spline shaft 1 is propelled in the axial direction of the spline nut 2.

  The axial length of the forcer 31, that is, the length of the forcer 31 along the arrangement direction of the coil members 32 is formed longer than the axial length of the spline nut 2. For this reason, the spline nut 2 is fixed to the central portion in the longitudinal direction of the forcer 31, and both ends in the longitudinal direction of the forcer 31 are exposed to the outside of the spline shaft 1 from the slit opening 12 without being covered by the spline nut 2. Yes.

  In such a structure, only the central portion in the longitudinal direction of the forcer 31 is supported by the spline nut 2, and when the forcer 31 is elongated to increase the thrust of the linear motor 3, the forcer 31 itself is bent. There is concern about contact with the magnet rod 30 due to deformation. However, since the metal reinforcing plate 34 is provided over the entire length of the forcer 31 and the forcer 31 is fixed to the spline nut 2 via the reinforcing plate 34, deformation of the forcer 31 is suppressed, and the magnet rod 30 and the forcer 31 are suppressed. It is possible to prevent contact.

  Further, since both ends of the forcer 31 in the longitudinal direction are exposed to the outside through the slit opening 12 of the spline shaft 2 without being covered by the spline nut 2, the forcer 31 is energized by energization of the drive current to the coil member 32. Even when heat is generated, heat dissipation from the forcer 31 can be promoted, and a reduction in thrust of the linear motor 3 during continuous operation can be prevented.

  On the other hand, as a result of increasing the forcer 31 and improving the thrust of the linear motor 3 as described above, if the spline shaft 1 exceeds the limit stop position and overruns the spline nut 2. It is assumed that the end of the forcer 31 hits the end cap 5 and the forcer 31 is damaged.

  Even when such a situation occurs, in order to prevent the forcer 31 from being damaged, the linear actuator unit is provided with a pair of protector plates 4 for protecting the forcer 31. FIG. 5 is a side view showing the forcer 31 with the protector plate 4 attached thereto. The protector plate 4 is a metal plate having a distal end portion 40 bent in a substantially L shape, and is attached to the reinforcing plate 34 of the forcer 31 so as to sandwich the spline nut 2 from the axial direction. With the protector plate attached, a gap is formed between the front end portion 40 of the protector plate 4 and the axial end surface of the forcer 31, while the rear end portion 41 of the protector plate abuts against the spline nut 2. ing. Further, the attachment of the protector plate 4 to the reinforcing plate 34 of the forcer 31 is accompanied by some play so that the external force acting on the protector plate 4 does not reach the reinforcing plate 34 and thus the forcer 31.

  By providing such a protector plate 4, when the spline shaft 1 is moved in the axial direction of the spline nut 2, the spline shaft 1 exceeds the limit stop position and overrun occurs. However, since the protector plate 4 collides with the end cap 5 prior to the forcer 31, the forcer 31 does not collide with the end cap 5, and the forcer 31 can be prevented from being damaged. Further, there is a gap between the front end portion 40 of the protector plate 4 and the end surface of the forcer 31, and the rear end 41 of the protector plate 4 is abutted against the spline nut 2. Even if it collides with the cap 5, the impact force is applied by the spline nut 2 assembled to the spline shaft 1 and does not act on the forcer 31. For this reason, it is possible to eliminate an adverse effect such as a change in the mounting posture and the mounting position of the forcer 31 with respect to the spline nut 2 due to the collision of the protector plate 4 with the end cap 5.

  Although the linear motor actuator having the spline shaft as the guide shaft of the present invention and the spline nut as the slide member of the present invention has been described in FIGS. 1 to 5, the application target of the present invention is not limited to this. For example, a track rail arranged on a fixed base is used as a guide shaft, a table mechanism that can reciprocate along the guide shaft is used as a slide member, a magnet member of a linear motor is used as the fixed base, and a forcer is used as the table mechanism. May be assembled.

It is a whole perspective view which shows the linear motor actuator of this invention. It is a side view of the linear motor actuator shown in FIG. FIG. 2 is a perspective view in which the microactuator shown in FIG. 1 is cut out perpendicularly to the longitudinal direction at the center of the spline nut. It is a perspective view which shows the forcer which comprises a linear motor. It is a side view which shows the state which mounted | wore the protector plate to the forcer shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Spline shaft, 2 ... Spline nut, 3 ... Linear motor, 4 ... Protector plate, 5 ... End cap, 12, 13 ... Slit opening, 30 ... Magnet rod, 31 ... Forcer, 32 ... Coil member, 33 ... Resin holder 34 ... Reinforcing plate

Claims (2)

A spline shaft that has a hollow portion and is formed in a cylindrical shape and has a slit opening and a rolling surface of the rolling element formed in the axial direction, and is arranged around the spline shaft through a number of rolling elements. A single spline nut that guides the spline shaft in the axial direction, a plurality of magnetic poles repeatedly arranged in the longitudinal direction, and a magnet rod that is supported at both ends in the hollow portion of the spline shaft, and the spline shaft A linear motor is arranged around the magnet rod in the hollow portion and coupled with the magnet rod. The linear motor is formed longer in the moving direction than the spline nut, and the central portion in the longitudinal direction is the slit of the spline shaft. A forcer combined with the spline nut through an opening,
The forcer is composed of a plurality of coil members wound around the magnet rod, a resin holder that integrally holds the coil members, and a reinforcing plate provided over the entire length of the resin holder. A linear motor actuator, wherein the linear motor actuator is fixed to the spline nut via a reinforcing plate. A pair of end caps are fitted to both axial ends of the spline shaft,
A protector plate for preventing contact between the forcer and the end cap is disposed on the reinforcing plate of the forcer, and one end of the protector plate is abutted against the end surface of the spline nut, while the other end is the spline nut. The linear motor actuator according to claim 1, wherein the linear motor actuator protrudes from an end face of the forcer with respect to a moving direction.

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