JPH08214529A - Linear motor - Google Patents

Abstract

PURPOSE: To provide a high-thrust linear motor without coil structure being complicated by arranging three pieces of position detecting elements at the intervals stipulated by the magnetic pole pitch of a permanent magnet, and also, forming them as separate bodies from three-phase flat coils. CONSTITUTION: A needle 16 has a coil 19a, where three pieces of flat coils LU1 , LW1 , and LV1 wound with a width one-sixth the magnetic pole pitch 1m of a permanent magnet 14 are arranged, being slid by the width of the coil, and coils 19b and 19c constituted likewise, and three position detecting elements 20 are provided at intervals 1h one-sixth the coil pitch 1c. And, three-phase current waves whose positions are slid by 120 deg. each by a driving circuit are made, and these are supplied to the flat coils LU1 , LW1 , and LV1 , whereby the needle 16 shifts continuously. As a result, even when the number of flat three- phase armature coils is increased, there is no necessity to provide position detecting elements at every coil, consequently the coil structure is not complicated, and a high-thrust linear motor can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor of a type in which a moving coil linearly moves in a magnetic gap formed by a permanent magnet.

[0002]

2. Description of the Related Art Conventionally, driving devices for positioning an object within a long stroke range of 10 cm to 100 cm are disclosed in, for example, Japanese Patent Publication No. 58-49100 and Japanese Utility Model Publication No. 63-93783. Such moving coil type linear motors are often used. In this linear motor, a plurality of permanent magnets magnetized in the thickness direction are arranged so as to face each other with different magnetization directions, and move in a direction perpendicular to the magnetic flux in a gap formed between the facing permanent magnets. It has a structure in which a moving coil assembly is arranged.

In such a linear motor, there is no center yoke in the magnetic circuit portion, and the magnetic flux forms a plurality of closed loops in the air gap so that the magnetic flux is not concentrated in a part of the magnetic path. A uniform magnetic flux density can be generated over the entire long stroke.

FIG. 4 is an explanatory view of essential parts showing a conventional linear motor. In FIG. 4, reference numeral 1 denotes a yoke, which is made of a ferromagnetic material such as an iron plate and has a flat plate shape. Reference numeral 2 denotes a permanent magnet, which is magnetized in the thickness direction, and is arranged and fixed in the longitudinal direction of the yoke 1 so that NS magnetic poles alternately appear on the surface. The yoke 1 formed as described above is disposed via the gap 3 so that the different poles of the permanent magnet 2 face each other. Reference numeral 4 denotes a support plate, which is fixed to both ends of the yoke 1 in the longitudinal direction in order to secure the gap 3. The supporting plate 4 is preferably made of the same ferromagnetic material as the yoke 1.

Next, 5 is a coil, which is formed by a flat multi-phase coil whose winding direction is orthogonal to the magnetic flux in the air gap 3. That is, a plurality of coils are connected to the permanent magnet 2
Are arranged so as to be slightly displaced in the arrangement direction, the direction of the magnetic pole is detected through a means such as a magnetic field detecting element, and the coil through which the current flows and the direction thereof can be switched. The coil 5 is integrally supported by a holder (not shown) to form a mover.

With the above structure, when a current is passed through the coil 5, the winding direction of the coil 5 is orthogonal to the magnetic flux generated by the permanent magnet 2. Therefore, the coil 5 moves in the longitudinal direction of the yoke 1 according to Fleming's left-hand rule. The movable element (not shown) that integrally supports the coil 5 receives the driving force of the yoke 1.
Move in the longitudinal direction.

Next, when a current in the opposite direction to the above is applied to the coil 5, a driving force in the opposite direction to the above acts on the coil 5, so that the mover moves in the opposite direction. Therefore coil 5
By selecting the direction of energization and its current,
The mover can be moved to a predetermined position.

[0008]

In the linear motor having the above-mentioned structure, the permanent magnet 2 is generally formed in a rectangular parallelepiped shape, and the cross-sectional area orthogonal to the moving direction of the coil 5 is the same.
That is, the thickness dimension and the width dimension are the same. In addition, a gap between a plurality of permanent magnets 2 and 2, the interposition of an adhesive,
The magnetic flux density is smaller than that in the middle portion of the permanent magnet 2 due to the short circuit of the magnetic flux and the like. And the permanent magnet 2
The magnetic flux distribution in the moving direction of the coil 5 as a whole is substantially arcuate.

Generally, in a motor having a permanent magnet field on the rotor side and a fixed armature on the outer side, in order to always keep the relationship between the magnetic flux of the rotor and the armature magnetomotive force vertical,
It is said that it is necessary to establish a sinusoidal armature current and form a sinusoidal gap flux distribution by a suitable control circuit. With this configuration, the torque generated by the motor depends only on the product of the maximum values of the armature current and the magnetic flux density, and torque that is irrelevant to the displacement angle of the rotor from the reference axis is generated. That is, it is possible to prevent the occurrence of torque ripple due to the displacement angle.

On the other hand, a linear motor is one in which the diameters of the rotor and armature are made infinite, and the above theory is naturally applied. Therefore, if the magnetic flux density distribution in the moving direction of the coil 5 in the permanent magnet 2 shown in FIG. 4 is formed in a sinusoidal shape, the torque ripple due to the moving position of the coil 5 can be eliminated, and a linear motor with excellent linearity can be obtained. Becomes

In the linear motor as described above, for example, in Japanese Utility Model Laid-Open No. 63-93783, in order to reduce the thrust ripple in the DC linear motor, the surface of the magnet facing the armature is formed into a gentle concave portion. Suggestions of contents are described. However, in the above proposed linear motor, a position detection element (magnetoelectric conversion element) is provided for each coil to reverse the direction of the current flowing through each coil, so it is necessary to provide each coil with a current control means. . Therefore, when the number of coils is increased for the purpose of obtaining high thrust, the structure becomes complicated.

The present invention solves the above-mentioned problems existing in the prior art, and even if the number of coils is increased, it is not necessary to provide a position detecting element (magnetoelectric conversion element) for each coil, and therefore the coil structure does not become complicated. , To provide a high-thrust linear motor.

[0013]

In order to solve the above problems, according to the present invention, a plurality of permanent magnets are arranged in parallel so that adjacent magnetic poles have different polarities and their magnetic pole faces are aligned. A position that detects the relative position between the permanent magnet and the polyphase coil, which is opposed to the permanent magnet via a magnetic gap and has a polyphase coil movably provided along the magnetic pole surface thereof. In a linear motor including a detection element and an energization switching unit that switches energization to the multiphase coil by the position detection element and a control circuit, the multiphase coil has a coil width defined by a magnetic pole pitch of the permanent magnet. A three-phase flat coil, and each phase of the three-phase flat coil is connected in series and each phase is Y-connected, and further associated with each three-phase flat coil individually. The number of position detecting elements formed separately from the said three-phase flat coil while spaced defined by the magnetic pole pitch of the permanent magnet adopts the technical means of.

With the above configuration, even when the number of armature coils of the linear motor is increased in order to obtain a high thrust, each phase is connected in series and each phase is connected in a Y shape, so that the connection configuration is The complexity is suppressed.
Further, the number of position detection elements (magnetoelectric conversion elements) is only three corresponding to each of the three-phase flat coils and provided separately from the three-phase flat coils, and with these three, three
Even if the number of phase-flattened coils is large, it is possible to provide a function of reversing the direction of the current flowing through each coil. Therefore, even if the number of coils is increased for the purpose of obtaining high thrust, it is possible to configure a moving coil linear motor with high thrust that can avoid the problem that the structure of the coil body becomes complicated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of the essential parts showing an embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a base, which is formed in a flat plate shape with a ferromagnetic material such as mild steel. Reference numeral 12 is a center yoke and 13 is a side yoke.
It is formed in the shape of a flat plate by the same material as the above, and is fixed on the base 11 with a space. Next, 14 is a permanent magnet, which is formed of, for example, a rare earth magnet in a shape and dimension as described later, and is provided with a center yoke 12 and a side yoke 1.
A plurality of magnetic poles are arranged on each of the facing surfaces of 3 so that the polarities of the adjacent magnetic poles are different from each other so that the different poles face each other through the magnetic gap 15.

In FIG. 1, the disposing direction of the permanent magnets 14 is a direction orthogonal to the paper surface. Next, 16 is a mover, and a coil frame 18 is fixed below the carriage 17, and the coil frame 18 is movably provided in the magnetic gap 15 in a direction orthogonal to the paper surface. The coil frame 18 is made of a non-magnetic material in order to prevent the generation of thrust ripples.

That is, for example, a resin (for example, glass-filled epoxy resin) substrate is mounted on the surface of an aluminum alloy frame (the surface of which is anodized for imparting insulating properties), and this substrate will be described later. The coil 19 is fixedly formed. If the coil frame 18 is made of a magnetic material or if a back yoke is present on the side of the mover 16, an imbalance due to the attractive force of the permanent magnet 14 occurs, which is one of the causes of the thrust ripple.
Reference numeral 19 denotes a coil, which is formed in a flat shape and is provided on both surfaces of the coil frame 18.

FIG. 2 is a perspective view of an essential part showing the coil frame 18 in FIG. 1, and the same parts are designated by the same reference numerals as in FIG. The coil 19 is, for example, a three-phase coil (Japanese Unexamined Patent Publication No. 62-62160
No. 193543), all the phases are connected in series, and the phases are connected in a Y-shape.

The linear motor of the present invention uses a polyphase coil as described above and supplies a sinusoidal drive current to the polyphase coil, but the power factor decreases as the number of phases increases. Therefore, since it is necessary to increase the input current, it is desirable to adopt the 2-phase or 3-phase energization method. That is, it is desirable that the linear motor of the present invention has a configuration in which two-phase or three-phase sine wave current output type drive circuits are combined.

FIG. 3 is a side view of an essential part showing the positional relationship between the position detecting element and the coil 19 in FIGS. 1 and 2.
The same parts are designated by the same reference numerals as those in FIGS. 1 and 2. In FIG. 3, the mover 16 has three flat coils Lu1, Lw1, Lv1 wound in a plane parallel to the paper surface with a width of ⅙ of the magnetic pole pitch lm of the permanent magnet 14 and displaced by the coil width. The coil 19a is arranged (the central portions of the flat coils do not overlap with each other), and the coils 19b and 19c have the same structure as the coil 19a.
In addition, the mover 16 has three position detecting elements 20 which are 1/6 of the coil pitch lc (equal to the magnetic pole pitch lm).
Are provided at intervals of lh.

These position detecting elements 20 are offset with respect to the flat coils Lu1, Lw1 and Lv1 to the interval l ', respectively, but since this offset state can be electrically processed, there is no problem in practical use. . Then, a drive circuit (not shown) creates a three-phase current waveform displaced by 120 °, and the three-phase current waveforms are generated by the flat coils Lu1, Lw1,
By supplying to Lv1 (the arrow in FIG. 3 shows the direction of the electric current), the mover 16 moves continuously.

In the case of three phases, theoretically, the distance lh between the position detecting elements 20 is determined by the coil pitch lc (the magnetic pole pitch lm).
It is set to ⅓ of the above), but in the example shown in FIG. That is, the flat coils Lu1, Lw1, Lv1
Etc., by reversing the energizing direction,
This is because they can be arranged at arbitrary positions for each (n is a positive integer) times.

Further, in this embodiment, the position detecting element 2
0 and a control circuit (not shown) switch or select the flat coil to be energized and the direction of current.
As the position detecting element 20, a known element such as a Hall element can be used. The control circuit also uses an ordinary permanent magnet as a field. For example, the same configuration as that of the synchronous AC servo motor may be used.

Further, in the present invention, the three-phase coil (19
Even when the a to 19c) are of the six-series type, the position can be detected by using the three position detecting elements 20. Therefore, the supplied current is a single-phase or three-phase sine wave current, and uses only the timing of inverting the Hall element from positive (negative) to negative (positive) (zero cross) as a synchronization means. .

When the two-phase energization method is adopted, the position detecting elements 20 are provided in the mover 16 at intervals of ¼ of the magnetic pole pitch lm, and the two-phase current waveforms displaced by 90 ° in the drive circuit are provided. It can be made and supplied to the coil.

[0026]

As described above, according to the present invention, each layer of the three-phase flat coil is connected in series and each phase is Y-connected, and further, three position detections individually associated with the three-phase flat coil are detected. Since the elements are arranged at intervals defined by the magnetic pole pitch of the permanent magnets and formed separately from the three-phase flat coil, the flat three-phase armature is provided in order to obtain high thrust. Even if the number of coils is increased, it is not necessary to provide a position detection element (magnetoelectric conversion element) for each coil, so the coil structure does not become complicated, and a high thrust linear motor can be provided. Is played.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention.

FIG. 2 is a perspective view of an essential part showing a coil frame in FIG.

FIG. 3 is a side view of essential parts showing the positional relationship between the position detection element and the coil in FIGS. 1 and 2.

FIG. 4 is an explanatory view of a main part showing an example of a conventional linear motor.

[Explanation of symbols]

 14 permanent magnet 16 mover

Claims (1)

[Claims] 1. A plurality of permanent magnets arranged in parallel so that the polarities of adjacent magnetic poles are different and the magnetic pole surfaces are aligned, and the permanent magnets face the permanent magnets via a magnetic gap and along the magnetic pole surface. And a position detecting element for detecting the relative position of the permanent magnet and the polyphase coil, and the position detecting element and a control circuit for the polyphase coil. In the linear motor, the multi-phase coil is a three-phase flat coil having a coil width defined by the magnetic pole pitch of the permanent magnet, and the three-phase flat coil. The respective phases are connected in series and the respective phases are connected in a Y shape. Further, three position detecting elements individually associated with each of the three-phase flat coils are defined by the magnetic pole pitch of the permanent magnet. Wherein while spaced 3
A linear motor characterized by being formed separately from the phase flat coil.