JP7158661B2 - vertical linear actuator - Google Patents

Description

The present invention is a vertical linear actuator capable of vertically driving a movable shaft slidably inserted through a coil unit fixed to a base, together with a work piece mounted by excitation of a coil fitted on the base, with a small thrust force. Regarding.

2. Description of the Related Art In recent years, a shaft-type linear actuator has attracted attention as an electric actuator that drives linearly. This type of linear actuator includes a movable shaft (shaft) in which a plurality of bar-shaped magnets are arranged in series, and a coil unit as a stator that slidably fits the movable shaft. The movable shaft is linearly driven by the excitation of the provided coil. With such a configuration, there is little cogging or speed unevenness, so its application in various fields is being studied. It is expected to be applied to various fields (semiconductor manufacturing equipment, etc.).

However, if the linear actuator is set vertically, if the power supply is cut off due to a power failure, etc., the thrust force on the movable axis, including the weight of the workpiece, will be zero. There is a risk that the work body will collide with the work table or the like and cause a failure.
By the way, in order to avoid such a collision, there is conventionally known a cylindrical linear motor provided with a damper mechanism as disclosed in Patent Document 1. This magnet has a magnetic field section (20) as a mover consisting of a pipe (21) in which a plurality of permanent magnets (22) are arranged in series, and a stator that slidably fits the magnetic field section (20). and a magnetic field section (20) is linearly driven by excitation of a coil (13) provided on the inner peripheral portion of the tubular frame (11). It has a structure in which cushioning members (26) are arranged inside both sides of the frame (11).

However, such a buffer member (26) employs a coil spring or a permanent magnet (26e) that utilizes the repulsive magnetic force of the same opposing magnetic poles inside the cylindrical frame (11) (see FIG. 11), thereby reducing miscontrol. It functions only as a so-called damper mechanism that can avoid collision between the end of the magnetic field part (20) and the bearing part (17) in the event of an abnormality such as runaway or power failure during acceleration. It has a configuration that does not affect driving. Therefore, if this product is installed in a vertical position and used, it must move upward against the weight of the stepped shaft (24) and the attached workpiece when reversing from descent to up. , it is necessary to use a coil (13) with a strong magnetomotive force and a permanent magnet (22) with a strong magnetic force. and the permanent magnet (22) are fixed inside the cylindrical frame (11), so the weight of the workpiece differs, and the magnetic force of the permanent magnets (26e and 22) varies. In accordance with the displacement of the separation width due to the repulsive magnetic force, the protrusion width of the small-diameter shaft portion (24b) protruding from the cylindrical frame (11) and the starting position of the workpiece mounted thereon relatively change. Therefore, there is a problem that the positioning adjustment cannot be performed, and the operation control for the initial drive setting of the linear motor cannot be adopted as it is.

International Publication No. 2013/069148

The present invention was devised to eliminate the above-mentioned problems, and the coil unit is provided vertically on a base, and the movable shaft is vertically driven together with the mounted work body. The workpiece is supported and received with a predetermined separation width by the repulsive magnetic force generated between the shaft-side magnet provided at the lower end of the movable shaft and the fixed-side magnet provided on the base with the same magnetic pole facing each other, The position can be held in a state where its own weight is canceled, and the lowering position of the movable axis due to vertical drive control is set to the range where the repulsive magnetic force always reaches, and the coil rises when the movable axis is reversed and moved upward. By assisting the magnetic force, the workpiece can be moved up and down with a small thrust force. Moreover, the magnets on the shaft side and fixed side are installed outside so that they can be adjusted and maintained, so the weight of the workpiece can be reduced. To provide a vertical linear actuator capable of easily adjusting positioning even when the stationary reference position of a workpiece changes due to displacement caused by magnetic pole repulsion due to external factors such as differences. there is

In order to solve the above-mentioned problems, a vertical linear actuator of the present invention has a movable shaft in which a plurality of bar-shaped magnets are arranged in series, and a plurality of coils slidably fitted on the movable shaft. and a coil unit provided thereon, wherein the movable shaft is driven forward and backward in a predetermined range of motion by excitation of the coil together with the work body to be mounted, wherein the coil unit is used as a base. A shaft-side magnet is provided at the lower end of the movable shaft to move the workpiece up and down together with the movable shaft. a fixed-side magnet is provided on the fixed side, and the repulsive magnetic force generated between the shaft-side magnet and the fixed-side magnet supports and holds the load of the work in the excitation OFF state with a predetermined separation width, The workpiece is set at a stationary reference position, and the lowered position of the movable shaft is set within the range of the repulsive magnetic force generated between the two magnets, so that the workpiece can be driven up and down with a small thrust force. The shaft-side magnet is fitted in a magnet-mounting portion protruding from the lower end of the movable shaft toward the lower surface of the work body, and the fixed-side magnet is fitted in a holder portion provided on the base or work table side. It is characterized in that each magnet mounting portion is provided outside the lower region of the movable shaft, where maintenance is possible, by fitting it to the inserted magnet mounting portion .

According to the present invention configured as described above, the coil unit is provided vertically on the base and vertically driven together with the work body to which the movable shaft is mounted. Due to the repulsive magnetic force generated between the shaft-side magnet and the fixed-side magnet provided on the base with the same magnetic pole facing each other, the workpiece is supported and received with a predetermined separation width, and the work is positioned in a state in which its own weight is cancelled. In addition to being able to hold the vertical drive control, the lower position of the movable shaft accompanying the vertical drive control can be set to the range where the repulsive magnetic force always reaches, and the drive control can be performed in the state where it is positioned as the stroke lower limit position for reverse upward movement. It assists the rising magnetomotive force of the coil when the axis is reversed and moves up, making it possible to drive the workpiece up and down with a small thrust. It does not require a powerful bar-shaped magnet, and the device itself can be made lighter and more compact, making it possible to provide an inexpensive device. Moreover, the shaft-side magnet , which rises with the workpiece, and the fixed-side magnet, which is provided on the base, are provided outside, including their respective magnet mounting portions, where maintenance is possible. It is possible to form a member and fix it to the tip cap with a screw, and not only can it be possible to suitably select and attach a magnet having the optimum magnetic force and size according to the balance with the work body. , the magnet mounting part of the fixed side magnet can be set to the holder part provided on the base so that it can be moved up and down by threading feed, and the weight of the workpiece and the magnet used Due to external factors such as differences in the strength of the magnetic force, including variations in mechanical accuracy due to surface magnetic flux and processing accuracy, etc., the separation width due to the repulsive magnetic force is displaced, and the movable shaft relatively protrudes due to this displacement. Even if there is a change in the movable range due to width change, the stationary reference position of the workpiece, or the lower stroke limit position, the workpiece can be adjusted according to the installation environment while keeping the separation width between both magnets constant at the site where it is used. By vertically adjusting the body, the stationary reference position of the work body can be easily repositioned.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a vertical linear actuator showing an embodiment of the present invention, in which (A) is a front view with a workpiece mounted thereon, and (B) is a side view of the same. It is a longitudinal cross-sectional view of the vertical linear actuator shown in FIG. 1(A) according to the embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION A vertical linear actuator, which exemplifies preferred embodiments of the present invention, will be described in detail below with reference to the drawings. 1 shows a state in which a workpiece is attached to a vertical linear actuator (A) is a front view, (B) is a side view, and FIG. 2 is a vertical cross-sectional view of the vertical linear actuator shown in FIG. 1 (A) 2. is. As shown in these figures, the vertical linear actuator 1 has a cylindrical pipe 21 made of a non-magnetic stainless steel pipe, and a plurality of donut-shaped bar magnets 2a having a hole in the center thereof. and a coil unit 3 as a stator to which the movable shaft 2 is slidably fitted. The movable shaft 2 is linearly driven by the excitation of the coil 32 provided on the outer peripheral portion of the cylindrical bobbin 31 through which is inserted. The bar-shaped magnet 2a may be a bar-shaped magnet that does not have a hole in its center.

A rear end cap 22 and a front end cap 23 are fitted to the upper end portion and the lower end portion of a cylindrical pipe 21 on the movable shaft 2, respectively. It is reinforced, and an arbitrary work body 5 such as a movable stage is attached to this reinforced portion.
Twelve coils 32, which are preliminarily wound in a doughnut-like shape, are inserted into the body of the cylindrical bobbin 31, and the coils 32 are U-phase, V-phase, and W-phase for three-phase drive. Each coil block is composed of four sets of three coils 32 of one phase. The number of sets of the coils 32 is arbitrary, and the coils 32 of each phase are connected in a predetermined pattern in which they are connected in series or in parallel. A donut-shaped insulating paper or an insulating resin sheet (not shown) may be interposed.

In the lower region of the movable shaft 2, there are a cylindrical shaft-side magnet 61 arranged on the movable shaft 2 side, and a cylindrical shaft-side magnet 61 arranged on the base 4 side or on a work table or the like separated from the base 4. A pair of magnets 6 consisting of a fixed side magnet 62 are coaxially arranged so that their N poles face each other and are separated from each other with a predetermined gap from the magnetic pole repulsion. The shaft-side magnet 61 is fitted to a magnet mounting portion 6a having a downward U-shaped cross section, which is integrally formed so as to protrude from the lower portion of the tip cap 23, so as to prevent magnetic interference with the bar-shaped magnet 2a at the lowest end. It is provided in the part where it does not occur.
Alternatively, the magnet mounting portion 6a may be formed as a separate member and fixed to the tip end cap 23 by screwing. By using separate members in this way, it is possible to suitably select and attach a magnet having an optimum magnetic force and size according to the balance with the workpiece. Moreover, the fixed-side magnet 62 may be coaxially opposed to the shaft-side magnet 61 and provided in a fixed state.

The fixed-side magnet 62 has a male threaded portion 6c protruding from its lower portion, and is mounted on the base 4 in a state of being fitted to the magnet mounting portion 6b formed in an upward U-shaped cross section. It is inserted into the holder portion 41 .
The holder portion 41 is formed in an upward U-shape in cross section, and a female screw portion 41a for screwing the male screw portion 6c is formed at the bottom portion thereof. With the male threaded portion 6c screwed into the threaded portion 41a, the male threaded portion 6c is set so as to be vertically movable and adjustable by screw feed by tightening and loosening the lower recessed groove 6c1 with a screwdriver or the like. In other words, the magnet mounting portions 6a and 6b are provided outside the lower region of the movable shaft 2 so that adjustment operations and maintenance work can be performed, and the workpiece 5 does not interfere with these adjustment operations and maintenance work. installed in the A lock nut may be provided on the female screw portion 41a in order to prevent the adjustment set position from being displaced due to vibration or the like caused by vertical movement.

Next, drive control of the vertical linear actuator 1 according to this embodiment will be described. In this way, in the state where the shaft-side magnet 61 and the fixed-side magnet 62 are arranged in the lower region of the movable shaft 2, when the vertical linear actuator 1 is not energized and the excitation is OFF, the movable shaft 2 and the workpiece are 5 (hereinafter simply referred to as the load or self weight of the workpiece 5) is supported and received with a predetermined separation width by the repulsive magnetic force generated between the shaft-side magnet 61 and the fixed-side magnet 62. The dead weight of the body 5 is canceled by the repulsive magnetic force, and the stop position is held in a balanced state. 3 from the lower surface of the workpiece 3 to the workpiece 5, and a movement stroke arbitrarily set within the movable range M is set for each coil block having a set of three-phase coils 32, or for an intermediate coil The block and the upper or lower coil block are paired, and are sequentially switched and controlled to linearly drive.

The excitation of the coil 32 is turned on from this stationary reference position to move the workpiece 5 upward to a predetermined elevated position, move it downward, and then reverse upward movement. The lowering position of the movable shaft 2 to be moved is always set in the range where the repulsive magnetic force generated between the shaft-side magnet 61 and the fixed-side magnet 62 reaches. In order to assist the magnetomotive force of 32, it is configured to be positioned as a stroke lower limit position for reverse upward movement. This stroke lower limit position may be set so as to coincide with the stationary reference position of the work piece 5. In consideration of the environment in which it is adopted and installed, the shaft-side magnet 61 and the base around the stationary reference position may be set. It may be set within the range of the repulsive magnetic force generated between it and the side magnet 62 . By setting the stroke lower limit position and controlling the drive in this way, it becomes possible to vertically drive the workpiece 5 with a small thrust force. The coils 32 with small magnetic force and the bar-shaped magnets 2a with small magnetic force can be adopted without requiring the bar-shaped magnet 2a with strong magnetic force, and the device itself can be made lighter and more compact. We can provide cheaper ones. The range over which the repulsive magnetic force between the two magnets extends includes at least the range in which the linear actuator can drive the workpiece with the assistance of the repulsive force of the two magnets.

On the other hand, in the vertical linear actuator 1, if the stroke lower limit position is always set to the position that utilizes the repulsive magnetic force in this way, there will be variations in the weight including variations caused by manufacturing errors, types, and sizes of the workpiece 5 itself. and the difference in the strength of the magnetic force, including variations in the mechanical accuracy due to the surface magnetic flux of the pair of magnets 6 used, processing accuracy, etc., or due to external factors such as the difference in the installation environment such as temperature. The separation width due to the repulsive magnetic force is not constant and is displaced, and the movable range M, the stationary reference position and the lower stroke limit position of the workpiece 5 are changed due to the relative change in the protrusion width of the movable shaft caused by the displacement. . Even if a plurality of vertical linear actuators 1 are installed on the same production line, this change may occur in each vertical linear actuator 1. In such a state where such a relative positional change occurs, the driving force set in advance at the time of shipment may not be used. Depending on the control, there is a fear that accurate motion control cannot be performed.

However, the fixed-side magnet 62 in this embodiment is configured to be able to be vertically moved and adjusted by screw feed by tightening and loosening the male screw portion 6c of the magnet mounting portion 6b. In other words, the fixed-side magnet 62 is moved upward to raise the workpiece 5 while maintaining the separation width constant against the repulsive magnetic force, and the work body 5 is moved downward while the separation width due to the repulsive magnetic force is kept constant. By lowering the work piece 5, it is possible to perform positioning adjustment while finely adjusting the work piece 5. By adjusting the vertical position of the work body 5, the lower stroke limit position of the movable shaft 2 can be made constant, and the initial position can be set in advance. Without changing the set drive control at all, an arbitrary stroke set within a movable range M is driven up and down with high precision, and the work body 5 is positioned and stopped with high precision at the raised and lowered positions. is configured so that

In the embodiment of the present invention constructed as described above, the movable shaft 2 of the vertical linear actuator 1 is moved together with the workpiece 5 by ON/OFF switching of the coils 32 of the coil unit 3 fixed to the base 4. In the vertical linear actuator 1 of the present invention, a shaft-side magnet 61 is provided at the lower end of the movable shaft 2, and the shaft-side magnet 61 is opposed to the base 4 or the work table so that the magnetic pole repels the shaft-side magnet 61. A fixed-side magnet 62 is provided, and the repulsive magnetic force generated between the shaft-side magnet 61 and the fixed-side magnet 62 supports and receives the load of the workpiece 5 in the excitation OFF state with a predetermined separation width. The workpiece 5 is held and set at the stationary reference position, and the lowered position of the movable shaft 2 is set within the range of the repulsive magnetic force generated between the two magnets 61 and 62, thereby driving the workpiece 5 up and down with a small thrust force. On the other hand, the shaft-side magnet 61 is fitted to a magnet mounting portion 6a that protrudes from the lower end of the movable shaft 2 to the lower surface of the workpiece 5, and the fixed-side magnet 62 is attached to the base 4 or the lower surface of the workpiece 5. By fitting the magnet mounting parts 6a and 6b to the holder part 41 provided on the work table side, the magnet mounting parts 6a and 6b can be placed outside the lower area of the movable shaft 2 where maintenance is possible. It is provided .

With this configuration, the coil unit 3 is arranged vertically on the base, and the vertical linear actuator 1 moves up and down together with the workpiece 5 to which the movable shaft 2 is mounted. The workpiece 5 is supported and received with a predetermined separation width by the repulsive magnetic force generated between the shaft-side magnet 61 provided on the base 4 and the fixed-side magnet 62 provided on the base 4 with the same magnetic pole facing each other. Not only can the position be held in a state where is canceled, but also the lower position of the movable shaft 2 due to vertical drive control is set to the range where the repulsive magnetic force always reaches, and the drive control is performed in a state positioned as the lower limit of the stroke for reverse upward movement. can be performed, assisting the rising magnetomotive force of the coil 32 when the movable shaft 2 is reversed upward, and it is possible to vertically drive the work body 5 with a small thrust. Since the coil 32 with strong magnetomotive force and the bar-shaped magnet 2a with strong magnetic force are not required, the device itself can be made lighter and more compact, and the device can be provided at a low cost.

In particular, a more compact vertical linear actuator 1 is selected by setting the upper limit of the upward movement of the workpiece 5 within a range supported by the repulsive force generated between the shaft-side magnet 61 and the base-side magnet 62. It becomes possible to
For example, when the repulsive force of both magnets at the stationary reference position was 50N, it was possible to drive and control a 4kg workpiece by a linear actuator with a rated thrust of 3.5N. The upper limit of the stroke in this case was about 8 mm upward from the stationary reference position. In the linear actuator sold by the applicant, in order to drive and control a load of 4 kg, a cylindrical neodymium magnet with a diameter of 8 mm is used instead of using a shaft using a cylindrical neodymium magnet with a diameter of 25 mm. It was possible to drive and control with the shaft that was in.
Moreover, the shaft -side magnet 61 rising together with the workpiece 5 and the fixed-side magnet 62 provided on the base 4 are provided outside, including the respective magnet mounting portions 6a and 6b, where maintenance is possible. The magnet mounting portion 6a of 61 can be formed of a separate member and fixed to the tip cap 23 by screwing. In addition, the magnet mounting portion 6b of the fixed side magnet 62 can be set to the holder portion 41 formed on the base 4 so that the vertical movement can be adjusted by screw feed. The repulsion is caused by external factors such as the difference in the strength of the magnetic force, including variations in mechanical precision due to the weight of the workpiece 5, the surface magnetic flux density of the two magnets 61 and 62 used, and the processing precision. The separation width due to the magnetic force is displaced, and the relative displacement causes a change in the range of motion M (a change in the protrusion width of the movable shaft 2) and a change in the stationary reference position and the stroke lower limit position of the workpiece 5. Also, at the site where it is used, the stationary reference position of the work body 5 can be easily adjusted by adjusting the work body 5 up and down according to the installation environment while keeping the distance between the two magnets 61 and 62 constant. can be repositionable to

In addition, the fixed magnet 62 can change the weight of the workpiece 5 or change the size of the two magnets 61 and 62 by inserting and setting the magnet mounting portion 6b in the holder portion 41 so that the vertical movement adjustment operation is possible. The stationary reference position of the workpiece 5 is adjusted up and down according to the relative change in the movable range M caused by the displacement of the separation width due to the repulsive magnetic force between the shaft-side magnet 61 and the like. configured as possible.
With this configuration, the fixed-side magnet 62 is operated upward to raise the workpiece 5 while maintaining the separation width constant against the repulsive magnetic force, and the separation width due to the repulsive magnetic force is made constant by downward movement. By lowering the work piece 5 while holding the work piece 5 in position, it is possible to finely adjust the work piece 5 while adjusting the positioning . Differences in the strength of the magnetic force, including differences in weight caused by manufacturing errors, types, and sizes of the magnets 5 themselves, variations in mechanical accuracy due to the surface magnetic flux and processing accuracy of the pair of magnets 6 used, etc. Due to external factors, the separation width due to the repulsive magnetic force is displaced, and the relative change in the movable range M (change in the protrusion width of the movable shaft 2) caused by the displacement, the stationary reference position of the work body 5, and the stroke lower limit position is changed, the stationary reference position of the workpiece 5 can be adjusted and changed while maintaining the separation width due to the repulsive magnetic force constant by adjusting the fixed side magnet 62 vertically. Moreover, by adjusting the vertical position of the workpiece 5, the lower limit position of the stroke of the movable shaft 2 is made constant, and accurate motion control can be performed without changing the initially set drive control. , the workpiece 5 can be accurately positioned and stopped at the set up position and the set down position.

1 Vertical Linear Actuator 2 Movable Axis 2a Bar Magnet 21 Cylindrical Pipe 22 Rear End Cap 23 Tip Cap 3 Coil Unit 31 Cylindrical Bobbin 32 Coil 4 Base 41 Holder Part 41a Female Screw Part 5 Workpiece 6 Magnet 61 Axis Side Magnet 62 Fixed side magnet 6a Magnet mounting portion 6b Magnet mounting portion 6c Male screw portion 6c1 Groove M Range of motion

Claims (3)

A movable shaft having a plurality of rod-shaped magnets arranged in series, and a coil unit having a plurality of coils arranged side by side on the inner circumference, the movable shaft being mounted on the movable shaft. A linear actuator configured to move forward and backward in a predetermined range of motion by energizing the coil together with the work body,
When the coil unit is mounted vertically on the base and the work body is vertically driven together with the movable shaft,
A shaft-side magnet is provided at the lower end of the movable shaft, and a fixed-side magnet is provided so as to face the base or work table so as to repel the shaft-side magnet,
By the repulsive magnetic force generated between the shaft-side magnet and the fixed-side magnet, the load of the workpiece in the excitation OFF state is supported and held with a predetermined separation width, and the workpiece is set at the stationary reference position. Along with
The lowering position of the movable shaft is set within the range of the repulsive magnetic force generated between the two magnets so that the workpiece can be vertically driven with a small thrust force.while
The shaft-side magnet is fitted to a magnet-mounting portion protruding from the lower end of the movable shaft toward the lower surface of the work body, and the fixed-side magnet is fitted to a holder portion provided on the base or work table side. In order to be fitted to the fitted magnet mounting portion, each magnet mounting portion is provided outside of the lower region of the movable shaft where maintenance is possible. A vertical linear actuator characterized by: According to claim 1, the fixed-side magnet is set by inserting the magnet mounting portion into the holder portion so that the magnet mounting portion can be vertically moved and adjusted . A vertical linear actuator, wherein the stationary reference position of the vertical linear actuator is configured to be vertically adjustable. 3. A vertical linear actuator according to claim 1 or 2, wherein the upper limit of the movement stroke of said workpiece is set within the range of repulsive magnetic force generated between said two magnets.

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