JPH02219455A - Linear motor supporting mechanism - Google Patents

Abstract

PURPOSE:To constitute a power saving contactless mechanism by forming a levitation permanent magnet of laminated piezoelectric elements, through an operational gap with respect to a stator, at the opposite side from a stator for thrusting a mover through a thrust generating magnetic circuit. CONSTITUTION:A mover 24 is mounting a thrust generating magnetic circuit 29 comprising magnetic poles 25a-25d, a coil 26, a permanent magnet 27, and a yoke 28 and moves in the longitudinal direction of the stator 21. A gap G1 is detected 36 and controlled 37 then power amplification 38 is carried out and a laminated piezoelectric elements 34 are controlled. The piezoelectric elements 34 are fixed to the movable table 33 of a base 30 and a gap G2 is formed with respect to the stator 21 through a yoke 32 and a levitation permanent magnet 31. Linear guides 35 comprising two rows of ceramic balls are arranged at the opposite sides of the mover 24 such that they can be displaced freely only in the straight direction. By such arrangement, a contactless power saving mechanism requiring no lubrication can be formed.

Description

[Detailed Description of the Invention] Summary Regarding a support mechanism for a linear motor, the purpose is to provide a non-contact type linear motor support mechanism that is small, power-saving, and has a long life.At least one magnetomotive force source using a permanent magnet or a coil is provided. In a linear motor that has a magnetic circuit for generating thrust including a thrust generating circuit and generates a thrust that causes the mover to move straight on the stator by magnetic force or electric current force, each of the magnetic openings for generating thrust is attached to the base, and the magnetic circuit for generating thrust is attached to the base. A levitation permanent magnet is provided on the opposite side of the magnetosphere path, facing the stator, with an operating gap in between, and the levitation permanent magnet is attached to the base via a laminated piezoelectric effect element.

INDUSTRIAL APPLICATION FIELD The present invention relates to a support mechanism for a linear motor, and more particularly to a support mechanism for a linear motor for use in vacuum or space applications, which has a magnetically levitated support mechanism that supports a thrust generating gap using magnetic force.

2. Description of the Related Art Many devices that move or position a controlled object on a one-dimensional or two-dimensional plane use a rotary motor and a mechanism that converts rotational motion into linear motion. In contrast, recent advances have been in the development of linear motors in which a controlled object is attached directly to the motor and the motor is driven in a straight line. Linear DC motor, linear pulse motor and linear m
Small linear motors such as electric motors are often used in FA and OA equipment that carries a load mass and moves in a straight line, such as in industrial robots with orthogonal coordinate systems, assembly and transfer equipment, and typewriter carriage drives. It is being

In these linear motors, it is necessary to support the mover with respect to the stator with a predetermined gap, and a gap support mechanism for generating thrust with a long life is desired.

Prior Art FIG. 9 is a partially cutaway front view of a conventional linear motor support mechanism, and FIG. 10 is a side view thereof.

In the figure, 1 is a stator, and 2 is a ferromagnetic substrate made of iron or the like.
A plurality of scale teeth 3 are provided on the top at equal pitch intervals. Reference numeral 4 denotes a mover, which has four magnetic poles 5as5b, 5c, and 5d made of a ferromagnetic material such as iron, and the teeth of the magnetic poles 5b, 5c, and 5d are each τ relative to the teeth of the magnetic pole 5a. They are arranged with a phase shift of /2, τ/4.3τ/4. Coils 6 are connected to the magnetic poles 5a to 5d, respectively.
is wound, and a permanent magnet 7 is provided on top of it. In addition, a ferromagnetic yoke 8 extends between two permanent magnets 7.
is provided.

Reference numeral 9 denotes a non-magnetic frame made of stainless steel or the like, and a primary side magnetic circuit assembly comprising the above-mentioned coil 6, permanent magnet 7, etc. is attached to this frame. Two hole-through shafts 10 are fixed to the non-magnetic frame 9, and a gap support roller 11 is rotatably attached to the shafts 10. The roller 11 comes into contact with the roller transfer surface 14 of the stator 1 and supports the thrust generating gap G. Furthermore, four shafts 12 are vertically fixed to the non-magnetic frame 9, and rollers 13 are rotatably attached to the shafts 12. The roller 13 is in contact with the side surface of the ferromagnetic substrate 2 and guides the stator 1 in a straight line.

In this way, in the conventional linear motor, the gap support roller 11 comes into contact with the roller rolling surface 14 of the stator 1, supports the thrust generation gap G, and drives the movable element 4 in a straight line relative to the stator 1. That's what I do.

Problems to be Solved by the Invention In the conventional support mechanism using gap support rollers, the magnetic attraction force between the mover and the stator due to the thrust generating permanent magnet is about 10 times as large as the thrust force, which places a burden on the support mechanism. There was a problem in that the life of the support mechanism was shortened, such as the increase in the amount of friction, resulting in peeling of the rolling surface of the rollers of the stator (flaking), etc. Furthermore, the gap support rollers, which are subjected to a large load, require lubricating oil, and because of the scattering and evaporation of lubricating oil, the lubricating oil is not suitable for support mechanisms of linear motors for vacuum or space applications.

To solve this problem, studies have recently begun on magnetic levitation using electromagnets, as seen in linear motor cars. A schematic diagram of this system is shown in FIG. In the figure, 15 is a stator, and a yoke 16 is provided. The movable element 17 has a thrust generating magnetic circuit 18, a linear guide electromagnet 19, and a levitation electromagnet 20. This linear motor levitates the movable element 17 relative to the stator 15 by the magnetic attraction force generated by the levitation electromagnet 20, and drives the movable element 17 in a straight line by the thrust generated by the thrust generating magnetic circuit 18.

However, with this configuration, the onboard load mass may fluctuate,
In applications where the permanent magnet used in the magnetic circuit for thrust generation has a large magnetic attraction force, dicol heat loss (copper loss) due to coil resistance tends to become large.

If a superconducting coil is used as an electromagnet to prevent this, there is a problem in that the device becomes larger due to cooling of the coil, etc.

The present invention has been made in view of these points, and its purpose is to provide a non-contact type linear motor support mechanism that is compact, power-saving, and has a long life.

Means for Solving the Problems A magnetic circuit for generating thrust is attached to a base, and a permanent magnet for levitation is provided on the opposite side of the magnetic circuit for generating thrust, with an operational gap in between the stator. A support mechanism for the linear motor is constructed by attaching the levitation permanent magnet to the base via the laminated piezoelectric effect element.

It is desirable to provide a detection means for detecting a change in the gap between the movable element and the stator, and to provide a control means for changing the voltage applied to the laminated piezoelectric effect element based on the detected value of the detection means. Furthermore, if a larger change in magnetic force is required by the levitation permanent magnet, a displacement magnification mechanism is provided between the laminated piezoelectric effect element and the levitation permanent magnet.

Function The present invention changes the magnetic force generated in the operating gap by displacing the levitation permanent magnet, magnetically levitates the mover, and provides a long-life non-contact type linear motor support mechanism. . The change in magnetic force with respect to the displacement of the levitation permanent magnet is large, and the magnetic force itself also needs to be large.

Therefore, a laminated piezoelectric effect element is used as a small displacement element suitable for displacing the levitation permanent magnet and capable of generating a large force with a small displacement. Since almost no current flows through the piezoelectric effect element when maintaining displacement and the electromechanical conversion efficiency is high, it is possible to realize a power-saving support mechanism. It also has the advantage of fast displacement response.

The detection means detects a change in the thrust generation gap, and the control means feedback-controls the voltage applied to the laminated piezoelectric effect element based on this detected value, and changes the operating gap according to the change in the thrust generation gap. Let them do it.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a first embodiment of the present invention, and FIG. 2 is a side view thereof. This first embodiment shows an example in which the support mechanism of the present invention is attached to a flat plate-shaped one-sided linear pulse motor. A stator 21 is composed of a plurality of scale teeth 23 formed at equal pitches on a ferromagnetic substrate 22 made of iron or the like.

24 is a movable element having a magnetic circuit 29 for generating thrust.

The thrust generating magnetic circuit 29 includes four magnetic poles 25 a, 25 b, 25 c, and 25 d made of a ferromagnetic material such as iron.
It has magnetic poles 25b and 25C.

The teeth of 25d are T/2, respectively, with respect to the teeth of magnetic pole 25a.
They are arranged with a phase shift of τ/4.3τ/4. A coil 26 is wound around each of the magnetic poles 25a to 25b, and a thrust generating permanent magnet 27 is provided above the coil 26. Further, a ferromagnetic yoke 28 is provided across the two permanent magnets 27. Yoke 28 is attached to base 30.

On the opposite side of the thrust generating magnetic circuit 29, two levitation permanent magnets 31 are arranged opposite to the stator 21 and separated by an operating gap G2.
is located. A yoke 32 is attached to the back surface of the levitation permanent magnet 31, and a closed magnetic path is formed between the yoke 32 and the stator 21. For this reason, the levitation permanent magnet 31
A magnetic bow force acts on the. The yoke 32 of the levitation permanent magnet 31 is attached to a movable table 33, and a laminated piezoelectric effect element 34 is provided inside this movable table 33. One end of the laminated piezoelectric effect element 34 is supported by a movable table 33, and a base 30 is mounted on the other end. As described above, the base 30 has a thrust generating magnetic circuit 29.
Fixed. The piezoelectric effect element 34 is always subjected to a force in the compression direction due to the magnetic attraction force of the levitation permanent magnet 31.

By applying a voltage to the laminated piezoelectric effect element 33, the floating permanent magnet 31 is displaced in the vertical direction, and the operating gap G2 is changed. The size of the thrust generation gap G1 can be adjusted by changing the magnetic attraction force at this time.

On both sides of the movable element 24, linear guides 35 made up of two rows of circulating ceramic balls are attached, respectively.

Essentially, no large load acts in the lateral direction, and the linear guide 35 only provides linear guidance, so no lubrication is required. This linear guide 35 restrains the lateral displacement of the movable element 24 as well as the three degrees of freedom of rolling (m-swing) and yawing (yaw). The degree of freedom in the direction of movement is controlled by a magnetic circuit for thrust generation.

Therefore, what is controlled by the displacement of the levitation permanent magnet 31 is only the remaining two degrees of freedom of the six degrees of freedom: vertical displacement and pitching. For this two-degree-of-freedom control, for example, a capacitive displacement meter 36 is provided at two locations in the front and rear of the movable element 24, the thrust generation gap G1 is detected by the capacitive displacement meter 36, and this detected value is sent to the control circuit 37. input.

The output of the control circuit 37 is amplified by the power amplifier circuit 38, and the voltage applied to the laminated piezoelectric effect element 31 is changed according to the change in the thrust generation gap G1.
Displace 4. In this way, in this embodiment, gear detection by capacitive displacement meter 36 → control circuit 37 → power amplification →
Two closed loop systems are formed for the displacement of the levitation permanent magnet 31 due to the displacement of the laminated piezoelectric effect element 34.

The laminated piezoelectric effect element 34 is, for example, a laminate of 60 pieces of piezoelectric ceramic having a square shape with a side of 5 mm and a thickness of 0.4 mm, and is elongated by 50 μm under no load at an applied voltage of 500 V), and does not undergo any thermal displacement. When restrained like this, it weighs 59 kgf.
Generates the force of. On the other hand, the magnetic attraction force F1 due to the permanent magnets for thrust generation and levitation is expressed by the following equation when considered using the simplified magnetic circuit model shown in FIG.

Here, φ: Magnetic flux μ0: Permeability of air gap ζ Permeability of permanent magnet glue coil S,:
Opposing area of air gap Sl: Cross-sectional area of permanent magnet HC: Coercive force of permanent magnet 11: Thickness of permanent magnet β, : Gap width Figure 4 is a graph showing the balance between the magnetic attraction force and the force generated by the laminated piezoelectric effect element. This is a graph showing the relationship between the force generated by the piezoelectric element and the displacement when the voltage applied to the piezoelectric element is changed, and the relationship between the magnetic attraction force of the levitation permanent magnet and the operating gap.

As shown in the graph in Figure 4, by increasing or decreasing the voltage applied to the multilayer piezoelectric effect element, the force generated by the multilayer piezoelectric effect element and the magnetic attraction force of the levitation permanent magnet are balanced, and the operating gap is reduced. It can be increased or decreased.

FIG. 5 shows the relationship between the magnetic attraction force of the levitation permanent magnet and the thrust generating permanent magnet, the operating gap, and the thrust generating gap in one graph. In equation (1), in the thrust generating permanent magnet, I! , large and S1 small, and for the levitation permanent magnet, Sm is large and β yo is small. At this time, as shown in FIG. 5, there is a difference in the slopes of the two characteristic curves. Force balance is maintained in the operating gap and the thrust generation gap where the magnetic attraction forces of both permanent magnets are equal. For example, in FIG. 5, when the magnetic attraction forces of both magnets are equal, the thrust generation gap is as small as 50 μm, and the operating gap is as large as 0.3+nm.

FIG. 6 shows a schematic configuration diagram of a second embodiment of the present invention,
This is an example in which a pair of displacement amplifying mechanisms 43 based on the lever principle are provided when the displacement is still small with only the laminated piezoelectric effect element 44. The thrust generating magnetic circuit 29 is shown as a block because it is the same as that in the first embodiment described above, and the stator 21
The scale teeth are also omitted. A yoke 42 is attached to the back surface of the levitation permanent magnet 41, and the yoke 42 is attached to the base 40 via a displacement magnifying mechanism 43 using the lever principle and a laminated piezoelectric effect element 44. 6th
In the figure, 40a and 40b are the fulcrums of the lever, l,
! ! 2, m, , m2 as shown in FIG. 6, the displacement magnification rate is (mI/11)x (mz/L). According to this embodiment, even if the mounted load mass changes greatly, by increasing the displacement of the levitation permanent magnet 41, the magnetic attraction force can be greatly changed, and support by the levitation permanent magnet 41 is made possible.

FIG. 7 shows a schematic configuration diagram of a third embodiment of the present invention.

This embodiment is an example in which a laminated piezoelectric effect element is used on one side of a flat plate-like double-sided linear motor.

The upper thrust generating magnetic circuit 29 constitutes a movable element, and its configuration is the same as that of the first embodiment shown in FIGS. 1 and 2, so a detailed explanation will be omitted. Also, scale teeth are formed at equal pitches on both the front and back surfaces of the stator 21°, but are omitted in the drawing for the sake of simplicity. The lower thrust generation magnetic circuit 45 includes four magnetic poles and coils, and a levitation and thrust generation permanent magnet 4 is mounted on each magnetic pole.
6 is provided. A yoke 4 is attached to the back of the permanent magnet 46.
7 is attached, and each yoke 47 is attached to a ferromagnetic member 4.
8. The ferromagnetic member 48 is the movable base 4
A laminated piezoelectric effect element 51 is provided between the movable base 49 and a base 50 to which the upper thrust generating magnetic circuit 29 is attached. In this embodiment, the yoke of the lower levitation permanent magnet of the first embodiment shown in FIG. 1 is connected, and the levitation permanent magnet also serves as a thrust generating permanent magnet.

FIG. 8 shows a schematic configuration diagram of a fourth embodiment of the present invention.

In this embodiment, the upper and lower magnetic circuits shown in FIG. 7 are further used on both side surfaces. In FIG. 8, 52 is a thrust generating magnetic circuit, which is attached to a base 53. 54 is a stator, and scale teeth provided on four surfaces are omitted. 55 is a permanent magnet for levitation and thrust generation, and each magnetic circuit includes a permanent magnet 56 for levitation and thrust generation. The yoke of the permanent magnet 56 for levitation and thrust generation is a movable table 57 and a laminated piezoelectric effect element 58.
It is attached to the base 53 via. In this embodiment, the linear guide 35 of the first embodiment shown in FIGS. 1 and 2 is not provided, and a complete magnetic levitation type support mechanism is used. The five degrees of freedom other than the moving direction of the mover are controlled by the displacement of a permanent magnet 56 for levitation and thrust generation.

Although each of the above-mentioned embodiments describes a flat linear motor, the support mechanism of the present invention is also applicable to a cylindrical linear motor. Also, although we have explained using a linear pulse motor as a magnetic circuit for generating thrust, it is not limited to linear pulse motors.
It is also applicable to linear DC motors and linear induction motors.

Effects of the Invention Since the linear motor support mechanism of the present invention is configured as described in detail above, it is possible to provide a non-contact type linear motor support mechanism that is small, power saving, and has a long life. Since it is a non-contact type, it does not require lubricating oil and can be applied to support mechanisms for linear motors for vacuum and space applications.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the first embodiment of the present invention, Fig. 2 is a side view of the first embodiment, Fig. 3 is an explanatory diagram showing a magnetic circuit model of a permanent magnet and an air gap, and Fig. 4 is a diagram showing the magnetic attraction force and A graph showing the balance of the forces generated by the laminated piezoelectric effect element. Figure 5 is a graph showing the relationship between the magnetic attraction force of the levitation permanent magnet and the thrust generation permanent magnet and the operating gap and the thrust generation gap. 7 is a schematic diagram of the second embodiment of the present invention, FIG. 7 is a schematic diagram of the third embodiment of the present invention, FIG. 8 is a schematic diagram of the fourth embodiment of the present invention, and FIG. 9 is a part of the conventional example. FIG. 10 is a side view of a conventional example, and FIG. 11 is a schematic diagram of a conventional example of magnetic levitation using electromagnets. ■...Stator, 4...Mover, 5a-25d...Magnetic pole, 6...Coil, 7...Permanent magnet for thrust generation, 8...Yoke, 9...Thrust generation Magnetic circuit for use, 0... Base, l... Permanent magnet for levitation, 2... Yoke, 3... Movable base, 4... Laminated piezoelectric effect element, 5... Linear guide, 6 ... Capacitive displacement meter, 1. Permanent magnet for levitation, 3. Displacement magnification mechanism, 4. Laminated piezoelectric effect element, 5. Magnetic circuit for levitation and thrust generation.・Laminated piezoelectric effect element, ... magnetic circuit for thrust generation, ... magnetic circuit for levitation and thrust generation, ... multilayer piezoelectric effect element.

Claims (3)

[Claims] (1) It has a thrust generating magnetic circuit (29) including at least one magnetomotive force source made of a permanent magnet or a coil, and the mover (24) moves straight on the stator (21) by magnetic force or current force. In the linear motor that generates thrust, the thrust generation magnetic circuit (29) is attached to the base (30), and the stator (21) is attached to the opposite side of the thrust generation magnetic circuit (24).
), a levitation permanent magnet (31) is provided across an operating gap (G2), and the levitation permanent magnet (31) is connected to a laminated piezoelectric effect element (34).
) A support mechanism for a linear motor, characterized in that it is attached to the base (30) via a support mechanism. (2) Detection means (
36) and a control means (37) for changing the voltage applied to the laminated piezoelectric effect element (34) based on the detection value of the detection means. support mechanism. (3) Laminated piezoelectric effect element (44) and levitation permanent magnet (
3. The linear motor support mechanism according to claim 1, further comprising a displacement amplifying mechanism (43) between the linear motor support mechanism (41) and the linear motor support mechanism (41).