JP7308504B2 - Cylindrical linear motor - Google Patents

Description

The present invention relates to a cylindrical linear motor that detects the position of a mover using a magnetic field generated by a drive magnet and performs feedback control.

A linear encoder (linear scale) is often used as position detecting means for position control of a mover (moving body) in a linear motor (Patent Document 1). However, linear encoders have problems such as being expensive, increasing the number of parts due to additional installation, and taking time and effort.

Therefore, a position detection device for a linear motor has been proposed that uses the magnetic field generated by a driving magnet on the stator side of the linear motor to replace the linear encoder (Patent Document 2). Such a position detection device generally has two magnetic sensors provided on the primary side of the linear motor at an interval of 1/4 wavelength of the magnetic field waveform generated by the secondary magnet, and processes the detection signals output by these magnetic sensors. A position signal is obtained by using the signal obtained by A magnetic sensor normally uses a Hall element, a magnetoresistive effect element, a differential transformer, or the like, and outputs an analog signal. This analog signal is converted into a digital signal, but an error occurs at this stage. The main errors include magnetic field waveform distortion, amplitude variation, and offset variation, all of which affect the position detection accuracy. Of these variations, the variation in amplitude is largely due to the variation in the distance between the primary side and the secondary side, and mechanical and mechanical measures are taken to reduce the variation. Variations in offset are largely due to temperature changes, and attempts have been made to improve the physical characteristics of the sensor and devised signal processing circuits. Since the distortion of the magnetic field waveform is determined by the magnet on the secondary side, it cannot be solved by processing the signal from the sensor. As will be described later, the present invention intends to improve the position detection accuracy by minimizing such distortion of the magnetic field waveform.

JP-A-2003-244929 JP 2012-253887 A JP 2010-288418 A

By the way, the position detecting device using the magnetic sensor as described above assumes that the magnetic field distribution generated by a plurality of driving magnets arranged in a row on the stator side in a uniaxial direction is a sine wave. However, the actual magnetic field distribution cannot be said to be an ideal sine wave, and has a considerably distorted waveform, which limits the positioning accuracy and resolution. Such limitations are particularly pronounced in the case of cylindrical linear motors.

As an example of a cylindrical linear motor, a stator having a plurality of stator windings provided via a cylindrical bobbin on the inner wall of a cylindrical casing, and a longitudinal hollow hole formed in the axial center of the stator. a pair of first and second bearings provided at both ends of the cylindrical casing for holding the movable shaft in a linear motion; A cylindrical linear motor has been proposed (Patent Document 3).

Furthermore, the present inventor has proposed a cylindrical linear motor having a Halbach array magnet as a stator, which is effective in reducing magnetic leakage and improving thrust.

In this cylindrical linear motor, a second cylindrical permanent magnet having anisotropy in the radial direction is combined with one end of a first cylindrical permanent magnet having anisotropy in the length direction, and a has anisotropy in the radial direction and at least one pair of Halbach array magnets combined with a third cylindrical permanent magnet having a magnetic pole direction opposite to the magnetic pole direction of the second cylindrical permanent magnet Prepare. A stator having a circular cross section integrally constructed by inserting a shaft body into a hole at the center of each of the first to third cylindrical permanent magnets; and a mover in which a plurality of toroidal coils concentric with the casing are arranged along the cylindrical casing to act as a cylindrical linear motor. .

An object of the present invention is to provide a cylindrical linear motor having a Halbach array magnet, which can generate a magnetic field having a magnetic flux distribution extremely close to a sine wave in the Halbach array magnet. It is in.

According to an aspect of the present invention, the cylindrical linear motor has two magnetic sensors provided at an interval of 1/4 wavelength of the magnetic field waveform generated by the driving magnet of the cylindrical linear motor, and the two magnetic A position detection device that uses a signal obtained by processing a detection signal output from a sensor to obtain a position signal, detects the position of the mover using the magnetic field generated by the driving magnet, and performs feedback control. In a cylindrical linear motor including a Halbach array magnet as the driving magnet, the Halbach array magnet has anisotropy in the radial direction on one end side of a first cylindrical permanent magnet having anisotropy in the length direction. A second cylindrical permanent magnet having anisotropy in the radial direction and a magnetic pole direction opposite to the magnetic pole direction of the second cylindrical permanent magnet is combined on the other end side. at least one set of arrayed magnet bodies formed by combining the cylindrical permanent magnets of the second cylindrical permanent magnet and the third cylindrical permanent magnet having the same length a, and the first cylindrical permanent magnet A cylindrical linear motor is provided, wherein the relationship between the length b of the permanent magnet and the length a is 0.7b≤a≤0.8b.

In the cylindrical linear motor according to the aspect described above, the arranged magnet body includes the second cylindrical permanent magnet having a magnetic pole direction in the radial direction toward the outer peripheral side on the north pole side of the first cylindrical permanent magnet. In combination, the third cylindrical permanent magnet having a magnetic pole direction in the radial direction toward the central axis is combined with the S pole side of the first cylindrical permanent magnet, and the Halbach array magnet body is composed of the An arrayed magnet assembly in which a plurality of sets of arrayed magnet bodies are combined in series, one set of two adjacent arrayed magnet bodies in the arrayed magnet assembly is the magnetic pole of the first cylindrical permanent magnet. The third cylindrical permanent magnet or the third cylindrical permanent magnet is combined with the other set so that the direction of the magnetic poles of the first cylindrical permanent magnets of the arranged magnet bodies of the other set is opposite to the direction of the magnetic poles of the first cylindrical permanent magnets. It is also possible to alternately share two cylindrical permanent magnets.

The cylindrical linear motor according to the above aspect has a circular cross-sectional fixed magnet integrally formed by inserting a shaft body into a hole at the center of each of the first to third cylindrical permanent magnets in the arrayed magnet assembly. and the mover, which is combined with the outer periphery of the stator so as to be able to move linearly along the stator, and has a plurality of toroidal coils concentric with the casing arranged along the casing in a cylindrical casing. , and may be configured to act as a cylindrical linear motor. In this case, the position detection device includes the two magnetic sensors mounted on the side of the mover to detect the magnetic field from the arrayed magnet assembly and output the detection signals having a phase difference of 90 degrees with each other. It is desirable to

In the cylindrical linear motor according to the above aspect, the first to third cylindrical permanent magnets in the arrayed magnet assembly are integrally movable in the direction of the central axis by inserting the shafts into the respective center holes of the first to third cylindrical permanent magnets. a stator having a circular cross section and a stator combined with the outer periphery of the mover along the central axis direction, and a plurality of annular coils concentric with the casing arranged along the casing in a cylindrical casing. , it may be configured to act as a cylindrical linear motor. In this case, the position detection device includes the two magnetic sensors attached to the stator side to detect the magnetic field from the arrayed magnet assembly and output the detection signals having a phase difference of 90 degrees with each other. It is desirable to

The cylindrical linear motor according to the above aspect is of a three-phase drive type, and is characterized in that the plurality of toroidal coils comprises at least one set of a combination of a U-phase coil, a V-phase coil, and a W-phase coil.

According to the present invention, there is provided a cylindrical linear motor having a Halbach array magnet that can generate a large magnetic field, and the Halbach array magnet can generate a magnetic field having a magnetic flux distribution that is extremely close to a sine wave. Cylindrical linear motors can be provided. This eliminates the need for an expensive device such as a linear encoder as a position detection device essential for position control of the mover, and also simplifies the parts and work for mounting the position detection device. As a result, the durability and maintainability of the device are improved.

FIG. 2 is a diagram for explaining permanent magnets used in the present invention and notation of their magnetization directions; A diagram for explaining an example of a Halbach array magnet body, which is a component when the present invention is applied to a cylindrical linear motor, where the array magnet body is arranged on the central axis side and an annular coil is arranged on the outer peripheral side. 1 is a perspective view for explaining the minimum configuration of the arrayed magnet bodies of FIG. FIG. 3 is a diagram for explaining magnetization directions of permanent magnets of a Halbach array magnet assembly formed by combining in series a plurality of Halbach array magnet bodies shown in FIG. 2 ; FIG. 4 is a diagram for explaining the magnetization direction of each permanent magnet when a stator of a linear motor is configured by using block-shaped permanent magnets in a linear Halbach array; When the relationship between the length a of the first cylindrical permanent magnet and the length b of the second and third cylindrical permanent magnets in the Halbach array magnet assembly shown in FIG. It is the figure which showed the measurement result of magnetic field distribution. When the relationship between the length a of the first cylindrical permanent magnet and the length b of the second and third cylindrical permanent magnets in the Halbach array magnet assembly shown in FIG. is a diagram showing the measurement results of the external magnetic field distribution of . When the relationship between the length a of the first cylindrical permanent magnet and the length b of the second and third cylindrical permanent magnets in the Halbach array magnet assembly shown in FIG. is a diagram showing the measurement results of the external magnetic field distribution of . FIG. 4 is a vertical cross-sectional view showing the main configuration of a cylindrical linear motor that employs the Halbach array magnets shown in FIGS. 2 and 3 as a stator; FIG. 2 is a diagram for explaining the basic configuration of magnetic poles of permanent magnets and three-phase coils in a cylindrical three-phase linear motor; FIG. 10 is a diagram showing the relationship between the coils added when the distance between magnetic poles NN in FIG. 9 increases and the arrayed magnet assembly composed of two arrayed magnet bodies illustrated in FIG. 2; BRIEF DESCRIPTION OF THE DRAWINGS It is the front view (FIG. (a)) and side view (FIG. (b)) for demonstrating the whole structural example of the magnet movable cylindrical linear motor by this invention. It is the front view (figure (a)) and side view (figure (b)) which showed another installation example of the position detection apparatus in FIG.

Before describing embodiments of the present invention, aspects of permanent magnets (hereinafter abbreviated as magnets) used in a cylindrical linear motor according to the present invention will be described with reference to FIG. As shown in FIG. 1B, the first cylindrical magnet 10 has anisotropy in its length direction (center axis direction). On the other hand, as shown in FIG. 1(a), the second and third cylindrical magnets 12 and 13 have anisotropy in their radial direction.

As for the magnetization direction, the first cylindrical magnet 10 is arranged so that the magnetic pole is oriented in the left direction of the drawing, as indicated by the arrow in FIG. ), the magnetic poles may be arranged in the rightward direction in the figure, as indicated by the arrows.

On the other hand, as indicated by arrows in FIG. 1(c), the second cylindrical magnet 12 has magnetic poles oriented radially from the center to the outer circumference of its cross section, and indicated by arrows in FIG. 1(d). As shown, the third cylindrical magnet 13 has magnetic poles oriented in the direction from the outer circumference toward the center of the cross section. Following the method of indicating the direction of current, the directions of the magnetic poles of the second and third cylindrical magnets 12 and 13 are shown on the right side of FIGS. symbols.

Next, referring to FIG. 2, a Halbach array magnet body (hereinafter, referred to as a (sometimes abbreviated as an arrayed magnet body) will be described. The arrows shown in FIG. 2 also indicate the orientation of the magnetic poles.

FIG. 2(a) is an example of the smallest unit of arrayed magnets in a cylindrical linear motor in which the arrayed magnets are arranged on the central axis side and the annular coils are arranged on the outer side thereof. According to this example, the first cylindrical magnet 10 having anisotropy in the length direction and the magnet combined with the end of the cylindrical magnet 10 on the N pole side (tip side of the arrow) are A second cylindrical magnet 12 having anisotropy in the radial direction and magnetized so as to face the outer periphery of the magnet is combined with the end portion of the first cylindrical magnet 10 on the S pole side (end side of the arrow). and a third cylindrical magnet 13 having anisotropy in the radial direction and magnetized so as to face the center of the magnet.

The arranged magnet body of this example exits the outer periphery of the second cylindrical magnet 12, enters the outer periphery of the third cylindrical magnet 13, and enters the first cylindrical magnet 10 from the third cylindrical magnet 13. The magnetic flux density on the side is much higher than that on the inner peripheral side.

FIG. 2(b) shows the arrayed magnet bodies shown in FIG. 2(a) left-right reversed, and can be considered as the same example as FIG. 2(a). The reason why FIG. 2(b) is shown will become clear from the description of FIG. 3 below.

FIG. 3 shows an example in which a plurality of sets (here, four sets) of minimum unit arrayed magnet bodies described in FIG. 2 are combined in series to constitute an arrayed magnet assembly. In this arrayed magnet assembly, one set (first set) of two adjacent arrayed magnet bodies (for example, the first set and the second set) has the magnetic pole direction of the first cylindrical magnet 10 as follows: A third cylindrical magnet is combined with the other set (second set) so that the direction of the magnetic poles of the first cylindrical magnet 10 of the arrayed magnet body of the other set (second set) is opposite to that of the first cylindrical magnet 10. 13 can be shared. Similarly, the second cylindrical magnet 12 can be shared between the second and third sets, and the third cylindrical magnet 13 can be shared between the third and fourth sets. In other words, the third cylindrical magnets 13 and the second cylindrical magnets 12 are alternately shared between two sets of adjacent arrayed magnet bodies.

As will be described later with reference to FIG. 8, this arrayed magnet assembly is suitable for constructing a cylindrical linear motor with movable coils by being fixedly arranged on the central axis side. Also, as will be described later with reference to FIGS. 11 and 12, this arrayed magnet assembly is arranged on the central axis side so as to be linearly movable in the axial direction to constitute a magnet-movable cylindrical linear motor. Also suitable for This is because the magnetic array shown in FIG. 2 has a feature that the magnetic flux density on the outer peripheral side of the cylindrical magnets 10, 12, and 13 is much higher than that on the inner peripheral side. .

The arrayed magnet assembly as shown in Fig. 3 can be used by inserting stainless steel shafts with screw portions at both ends through the holes in the center of all the cylindrical magnets and fixing both ends with nuts. Needless to say, this is only an example and the present invention is not limited to this.

By the way, when the stator of a linear motor is constructed by using block-shaped magnets in a linear Halbach array, as shown in FIG. By using it, the magnetic flux distribution of the magnetic field can be approximated to a sine wave.

On the other hand, when assembling arrayed magnets for a cylindrical linear motor, radially anisotropic cylindrical magnets and axially anisotropic cylindrical magnets can be manufactured relatively easily, Cylindrical magnets are difficult to manufacture. In the case of an arrayed magnet body in which this 45-degree directional anisotropic cylindrical magnet is inserted, the generated magnetic field is infinitely close to a sine wave, and the harmonic component is at a level that is difficult to measure. However, without inserting a 45 degree directional anisotropic cylindrical magnet, some harmonic components are generated and the sine wave is distorted. If this happens, the detection accuracy of the position detection device using a magnetic sensor that utilizes the magnetic field distribution from the arrayed magnets will be lowered, making it difficult to increase the resolution.

With respect to such problems, the present inventor conducted various trials and measurements and repeated studies. We have reached the knowledge that by selecting the ratio, the magnetic flux distribution of the generated magnetic field can be approximated to a sine wave.

Specifically, from the left side explained in FIG. Using an arrayed magnet body (hereinafter referred to as an arrayed magnet body for measurement) composed of a combination of magnets 12, the axial length b of the first cylindrical magnet 10, the length of the second and third cylindrical magnets 12 and 13 As a result of measuring the magnetic flux density by changing the lengths a and b as the axial length a in various combinations, the following measured values were obtained.

(First example: when a=b)
A radially anisotropic cylindrical magnet with an outer diameter of 23.8 mm, an inner diameter of 10.0 mm, and a length of 11.0 mm, and an axially anisotropic cylinder with an outer diameter of 23.8 mm, an inner diameter of 10.0 mm, and a length of 11.0 mm. The magnetic flux density on the surface of the magnetic body was measured with a gauss meter by constructing the shaped magnet like the arrayed magnet body for measurement explained in FIG. The results are shown in FIG. The strain rate is 2%. The sine wave is shown by the dashed line and the measurement results by the solid line, which almost overlap.

(Second example: when a=0.68b)
A radially anisotropic cylindrical magnet with an outer diameter of 23.8 mm, an inner diameter of 10.0 mm, and a length of 11.0 mm, and an axially anisotropic cylinder with an outer diameter of 23.8 mm, an inner diameter of 10.0 mm, and a length of 16.0 mm. The magnetic flux density on the surface of the magnetic body was measured with a gauss meter by constructing the shaped magnet like the arrayed magnet body for measurement explained in FIG. The results are shown in FIG. The strain rate is 0.6%. In this example as well, the sine wave is indicated by a dashed line and the measurement results are indicated by a solid line, but they almost overlap each other.

(Third example: when a=0.5b)
A radially anisotropic cylindrical magnet with an outer diameter of 23.8 mm, an inner diameter of 10.0 mm, and a length of 11.0 mm, and an axially anisotropic cylinder with an outer diameter of 23.8 mm, an inner diameter of 10.0 mm, and a length of 22.0 mm. The magnetic flux density on the surface was measured with a gauss meter by arranging the shaped magnet like the arrayed magnet body for measurement described in FIG. The results are shown in FIG. The strain rate is 4.2%. In this example as well, the sine wave is indicated by a dashed line and the measurement results are indicated by a solid line, but they almost overlap each other.

From the above measurement results, the relationship between the length b of the first cylindrical magnet 10 and the length a of the second and third cylindrical magnets 12, 13 is preferably 0.5b≤a≤b, and 0.5b≤a≤b. It was found that 7b≤a≤0.8b is more preferable. On the other hand, from the viewpoint of strain rate, it is preferably within 5%, more preferably within 2%.

Next, with reference to FIG. 8, an embodiment of a coil-movable cylindrical linear motor according to the present invention will be described.

FIG. 8 is a cross-sectional view of a cylindrical linear motor using an arrayed magnet assembly as shown in FIG.

In this embodiment, the arranged magnet assembly side is the stator and the annular coil side is the mover, but as will be described with reference to FIGS. It is also possible to have children.

As the cylindrical magnet used in this embodiment, a cylindrical Nd-Fe-B magnet (first cylindrical magnet 10) and a radially anisotropic cylindrical Nd-Fe-B magnet (the second and third cylindrical magnets 12 , 13), which are merely examples, and needless to say, the present invention is not limited to these numerical values. Also, the magnets may be Nd-Fe-B magnets, Sm-Co magnets, ferrite magnets, or other permanent magnets.

FIG. 8 is a cross-sectional view of a stator and mover in a three-phase linear motor (cylindrical linear motor), particularly a vertical cross-sectional view along the central axis of the stator. Hereinafter, the term "center axis" means the center axis of the stator unless otherwise specified. It is desirable that the stator has a circular cross-section and the mover has a ring-shaped cross-section, but this is not the only option, as long as the cross-sectional shapes of the stator and the mover are compatible so as not to hinder mutual movement.

The stator 30 is formed by connecting a plurality of sets of arranged magnet bodies described in FIG. 2, here five sets in series. That is, as described with reference to FIG. 3, one set of two adjacent arrayed magnet bodies has the magnetic pole orientation of the first cylindrical magnet 10 that is the same as that of the other set of arrayed magnet bodies in the first cylindrical shape. The third cylindrical magnet 13 and the second cylindrical magnet are alternately shared by combining them in the other set so that the direction of the magnetic poles of the magnet 10 is opposite. That is, the first and second sets share the third cylindrical magnet 13, the second and third sets share the second cylindrical magnet 12, and the third and fourth sets share the third magnet. The second cylindrical magnet 13 is shared between the fourth and fifth sets, and the second cylindrical magnet 12 is shared between the fourth and fifth sets.

The number of sets of arrayed magnet bodies is determined by the stroke of the mover.

An example of a method of constructing an arrayed magnet assembly by connecting a plurality of sets of such arrayed magnet bodies in series is as follows.

A nut 41A is attached to one end side of a round bar-shaped center shaft 40 having male threads at least near both ends thereof. Subsequently, the first to third cylindrical magnets are arranged in 12-10-13-10-12-10-13-10-12-10 to form an arrayed magnet assembly consisting of five sets of arrayed magnet bodies. -13 are mounted on the center shaft 40 in order. A male screw may be formed over the entire length of the center shaft 40 .

After mounting the cylindrical magnets for the five sets of arrayed magnet bodies, a nut 41B is mounted on the male screw on the other end side of the center shaft 40 to fasten the cylindrical magnets together. Tightening with a nut is preferably done with a double nut so that loosening does not occur later.

Next, the arrayed magnet assembly integrated as described above is inserted into the cylindrical casing 50 . It is preferable that the casing 50 has an inner diameter and a small thickness so as to be in close contact with the outer circumference of the arrayed magnet assembly.

Both ends of the casing 50 are covered with lid members 42A and 42B, and seals such as O-rings are provided between the casing 50 and the lid members 42A and 42B when it is necessary to keep the inside of the casing 50 airtight. It is preferable to provide a material or to seal by a method such as brazing.

The center shaft 40 and the casing 50 are made of non-magnetic material such as stainless steel, aluminum and brass. Moreover, the stator 30 is usually fixed to a base or the like at both ends thereof.

Six annular (including cylindrical) coils 80-1U, 80-1V', 80-1W, 80-2U', 80-2V, 80- A cylindrical mover 100 having 2W′ attached to a coil casing 90 is combined so as to move linearly along the stator 30 . Note that U', V', and W' indicate that the winding directions are opposite. Each of the six toroidal coils is wound around a bobbin, and the windings are star-connected or delta-connected and connected to a three-phase power source (not shown) and to a control device (not shown).

Here, the relationship between the permanent magnets and the coils in the linear motor will be briefly described with reference to FIGS. 9 and 10. FIG.

Generally, the relationship between the magnetic poles of magnets applied to a three-phase linear motor using magnets and the U-phase coil, V-phase coil, and W-phase coil is as shown in FIG. That is, the U-phase coil, the V-phase coil, and the W-phase coil correspond to the magnetic poles NN, and the length between the magnetic poles NN = (U-phase coil length + V-phase coil length + W-phase coil length). . Also, the coil length of each phase=(length between magnetic poles NN)/3.

When the length between the magnetic poles NN is long, it can be arranged as shown in FIG. As shown in FIG. 10, there are six coils in total, two for each of the U, V, and W phases between the magnetic poles NN. The basic arrangement of the coils is U-phase-V'-phase-W-phase-U'-phase-V-phase-W'-phase, and the number of coils is 3 (6, 9, 12, . . . ). is exceeded, this basic configuration is repeated. As described above, the V', U', and W' phases have their winding directions reversed. Coil length of each phase=(length between magnetic poles NN)/6.

FIG. 10 shows the relationship between such magnetic poles NN, six coils forming three phases, and an arrayed magnet assembly obtained by combining two sets of the arrayed magnet bodies described with reference to FIG.

Although the cylindrical linear motor of FIG. 8 shows six toroidal coils, as mentioned above, the minimum number of toroidal coils required to construct a three-phase cylindrical linear motor is three. In other words, the coils on the mover side are set in units of three-phase sets of U-phase, V-phase, and W-phase, and a plurality of sets are installed according to the required thrust. For example, the total length of the six toroid coils is (the length of the second or third cylindrical magnet x 2 + the length of the first cylindrical magnet x 2). 3, the movable distance range of the cylindrical linear motor is (total length of the arrayed magnet assembly−total length of the six annular coils).

The mover 100 is assembled around the casing 50 via a bearing or the like so as to be able to move linearly. However, it is not limited to these. Further, the mover 100 is provided with a flexible power cable for connecting with a three-phase power supply, and the connection form between the coil and the three-phase power supply is the gist of the present invention, including the star or delta connection form of the windings. Therefore, detailed description is omitted. This also applies to the examples shown in FIGS. 11 and 12, which will be described later.

A position detection device 200 is installed on the mover 100 so as to be close to the surface of the casing 50 and extend parallel to the direction of movement thereof. The narrower the distance between the position detection device 200 and the casing 50, the better. In the arrangement shown in FIG. 12, which will be described later, the distance from the casing 50 is about 20 mm, but there is no problem. The position detection device 200 moves together with the mover 100 and has first and second magnetic sensors S1 and S2 for detecting the magnetic flux density on the surface of the arranged magnet assembly (casing 50). Hall elements, magnetoresistive elements (MR elements), differential transformer coil sensors, etc. are used as magnetic sensors. The first magnetic sensor S1 detects the magnetic flux density of the sinusoidal magnetic field generated on the surface of the arrayed magnet assembly (casing 50) and outputs a first detection signal. The second magnetic sensor S2 detects the magnetic flux density of the sinusoidal magnetic field generated on the surface of the arrayed magnet assembly (casing 50), and detects a second magnetic field having a phase difference of 90 degrees with respect to the first detection signal. Outputs a detection signal. For this reason, the distance between the first magnetic sensor S1 and the second magnetic sensor S2 in the movement direction is set to 1/4 of the magnetic pole pitch (N pole to N pole). Such a position detection device 200 has the advantage of being less susceptible to ambient temperature changes, gap changes, and the like.

A control form including position control of the mover 100 executed by a control device (not shown) using the first and second detection signals from the position detection device 200 is well known (for example, Patent Document 2). Description is omitted.

Further, since the operation principle of the cylindrical linear motor is the same as that of the conventional cylindrical linear motor, detailed explanation is omitted.

The inner diameter of the coil casing 90 is larger than the outer diameter of the casing 50, and there is a small gap between the outer circumference of the arrayed magnet assembly (casing 50) and the inner circumference of the annular coil, strictly speaking, the inner circumference of the coil casing 90. It is formed.

A gap is provided between the inner circumference of the casing 50 and the outer circumference of the arrayed magnet assembly, and a plurality of holes penetrating in the direction of the central axis are provided in the cover members 42A and 42B at equal angular intervals. The stator 30 side can be cooled by introducing refrigerant such as compressed air from the hole on the one side and discharging the refrigerant from the hole on the other side.

With the configuration as described above, position control and speed control are performed by controlling the current flowing through the three-phase annular coils 80-1U, 80-1V', 80-1W, 80-2U', 80-2V, and 80-2W'. By doing, it can be operated as a cylindrical linear motor.

The cylindrical linear motor having the above configuration uses the cylindrical Halbach array magnet described in FIGS. 2 and 3, so that most of the magnetic flux generated is Since it acts on the side, that is, the toroidal coil, it is possible to reduce magnetic leakage and improve energy efficiency. About 1.2 to 1.5 times more thrust can be obtained than with a motor.

With reference to FIG. 11, an example of the overall configuration of a magnet movable cylindrical linear motor will be described.

This cylindrical linear motor has a plurality of toroidal coils described in FIG.

Specifically, in order to form the mover 400 in which the arrayed magnet assembly is arranged along the length direction (center axis direction) on the inner wall of the circular cross-sectional space of the casing 50 described in FIG. The casing 50 is arranged in the inner space of the plurality of toroidal coils at 300 (the inner space of the coil casing 90 in FIG. 8) so as to be linearly movable along the central axis, and the legs 410 are fixed to both ends of the casing 50. A linear guide 510 fixed on the table 500 guides the linear motion of the mover 400 via the leg portion 410 of the table 500 .

In this example, the position detection device 200 is installed on the stator 300 side so as to extend parallel to the movement direction of the mover 400 while being close to the surface of the casing 50, and is positioned on the surface of the moving arrayed magnet assembly (casing 50). It is configured to detect the magnetic flux density of the generated sinusoidal magnetic field.

FIG. 12 is a diagram showing another installation example of the position detection device. In this example, the position detection device 200' is installed on the stator 300 main body. Therefore, although the position detection device 200' is separated from the surface of the arrayed magnet assembly (casing 50), it has been confirmed that the detection accuracy is not hindered. Of course, the position detection device 200 ′ has exactly the same configuration as the position detection device 200 . In this case, the length in the moving direction of the stator including the position detecting device is shorter than in the case of FIG. 8, so the effective length is longer than the total length of the arrayed magnet assembly.

Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and illustrated configurations.

INDUSTRIAL APPLICABILITY The present invention can be effectively used in general cylindrical linear motors using Halbach array magnets, particularly in cylindrical linear servo motors.

10 first cylindrical permanent magnet 12 second cylindrical permanent magnet 13 third cylindrical permanent magnet 30, 300 stator 40 center shaft 41A, 41B nut 50 casing 80-1U, 80-2U', 80-1V ', 80-2V, 80-1W, 80-2W' Annular coil 90 Coil casing 100, 400 Mover 200, 200' Position detector 410 Leg 510 Linear guide S1, S2 Magnetic sensor

Claims (7)

A cylindrical linear motor having two magnetic sensors provided at an interval of 1/4 wavelength of a magnetic field waveform generated by a driving magnet of the cylindrical linear motor, and processing detection signals output from the two magnetic sensors. A Halbach array magnet as the driving magnet, wherein the position of the mover is detected using the magnetic field generated by the driving magnet and feedback control is performed by a position detection device that uses the signal obtained by the above as a position signal. In a cylindrical linear motor with a body,
In the Halbach array magnet body, a first cylindrical permanent magnet having anisotropy in the length direction is combined with a second cylindrical permanent magnet having anisotropy in the radial direction on one end side, and a has anisotropy in the radial direction and at least one set of arrayed magnet bodies formed by combining a third cylindrical permanent magnet having a magnetic pole direction opposite to the magnetic pole direction of the second cylindrical permanent magnet. ,
the second cylindrical permanent magnet and the third cylindrical permanent magnet have the same length a;
A cylindrical linear motor, wherein the relationship between the length b and the length a of the first cylindrical permanent magnet is 0.7b≤a≤0.8b. The arranged magnet body combines the second cylindrical permanent magnet having a magnetic pole direction in the radial direction toward the outer peripheral side to the N pole side of the first cylindrical permanent magnet, and the first cylindrical permanent magnet Combining the third cylindrical permanent magnet having a magnetic pole direction in the radial direction toward the central axis side on the S pole side of the magnet,
As the Halbach arrayed magnets, an arrayed magnet assembly in which a plurality of sets of the arrayed magnets are combined in series is provided. are combined with the other set so that the direction of the magnetic poles of the cylindrical permanent magnets of the other set is opposite to the direction of the magnetic poles of the first cylindrical permanent magnets of the arrayed magnet bodies of the other set. 2. The cylindrical linear motor according to claim 1, wherein the three cylindrical permanent magnets or the second cylindrical permanent magnets are alternately shared. a stator having a circular cross section integrally constructed by inserting a shaft body into a hole at the center of each of the first to third cylindrical permanent magnets in the arrayed magnet assembly;
The movable element is combined with the outer peripheral side of the stator so as to be linearly movable along the stator, and has a cylindrical casing in which a plurality of annular coils concentric with the casing are arranged along the casing. 3. A cylindrical linear motor according to claim 2 , wherein the cylindrical linear motor is configured to act as a linear motor. The position detection device includes the two magnetic sensors attached to the mover to detect the magnetic field from the arrayed magnet assembly and output the detection signals having a phase difference of 90 degrees with each other. Cylindrical linear motor according to claim 3 . the mover having a circular cross section integrally movable in the direction of the central axis by inserting a shaft body into a hole at the center of each of the first to third cylindrical permanent magnets in the arrayed magnet assembly;
A stator, which is combined with the outer circumference of the mover along the central axis direction and has a plurality of annular coils concentric with the casing disposed along the cylindrical casing, acts as a cylindrical linear motor. 3. The cylindrical linear motor according to claim 2 , characterized in that it is configured to The position detection device is Saidstatormounted on the side to detect the magnetic field from the arrayed magnet assembly and have a phase difference of 90 degrees from each otherSaidOutput detection signalSaidIncludes two magnetic sensorsMuko6. The cylindrical linear motor according to claim 5, characterized by: 3. The cylindrical linear motor is of a three-phase drive type, and the plurality of toroidal coils comprise at least one set of a combination of a U-phase coil, a V-phase coil, and a W-phase coil. Or the cylindrical linear motor according to 5.

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