JPH0635659Y2 - Movable magnet type linear DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a movable magnet type linear DC motor which is thin and capable of moving at high speed.

[Conventional technology]

Linear DC motors have attracted attention as a means for directly driving high-speed linear motion, and conventional linear pulse motors are often used for disk read head drive, printer head drive, XY stage drive, etc. The use of linear direct current motors has been promoted for the purpose of realizing this.

On the other hand, also in textile machines, members that perform linear motion, such as knitting needles of knitting machines and needles of sewing machines, are used. For example, in a conventional flat knitting machine, a carriage is reciprocated as is well known, and a knitting needle is caused to perform a reciprocating linear motion by a cam incorporated in the carriage, thereby performing a knitting operation.

[Problems to be solved by the device]

For example, in the above-mentioned flat knitting machine, since the weight and shape of the carriage are large, there is a limit in improving productivity by increasing the reciprocating speed of the carriage and increasing the number of yarns. Therefore, if the reciprocating linear movement of the knitting needle is performed by connecting an actuator such as a linear motor to each knitting needle, knitting at a significantly higher speed than in the past can be performed. As described above, it is considered possible to achieve a remarkably high speed by using the linear motor for driving the linear motion member in not only the flat knitting machine but also various textile machines. However, linear motion members in textile machines are generally arranged in a narrow space or densely arranged within a predetermined width, and therefore the linear motor used is small and particularly thin. Need.

From this point of view, when a conventionally known linear motor is examined, there are various problems, and the same applicant as the applicant of the present invention has one of the means for solving them, and the actual application was filed on June 10, 1986. -87199 (Shokaisho 62-198876) "thin linear DC motor" in the specification. However, for example, in the case of an 8 mm thick thin linear DC motor proposed in the specification of Japanese Utility Model Publication No. 61-87199 (Japanese Utility Model Publication No. 62-198876), the thickness of the mover yoke for the field magnet is Since the thickness is as thin as 1.5 mm, the yoke causes magnetic saturation, and there is a leakage magnetic flux to the outside of the yoke. This is the actual development Sho 61-871
An example of a thin movable magnet type linear DC motor with a thickness of 8 mm proposed in the specification of No. 99 (Shokaisho 62-198876) will be described as an example.

As shown in FIG. 2, four field magnets 3 each having a magnet width Pm of one pole are arranged on the mover yoke 2 so that their polarities are alternately arranged to form a mover. A plurality of coils 4 are arranged in a line on the stator yoke 1 along the moving direction of the mover at intervals of 4/3 Pm, and are displaced from the center of the coil by 1/2 Pm to the right or left (see FIG. 2). Then, a magnetic sensor 5 for detecting the polarity of the field magnet is arranged at a position (shifted to the right) to form a stator.

In the movable magnet type linear DC motor, the conventional method is to use four field magnets having the same width as the four-pole field magnet 3 as shown in FIG. It was noticed that the magnetic flux leaking from the mover yoke 2 in this case was larger at both ends than in the central part, and as a result of examination of the cause, as shown in FIG. A magnetic path is formed in the mover yoke 2 with the different poles of the magnet. However, since there is no opposite pole opposite to the range of about 1/2 Pm from both ends, the magnetic flux passing through the stator side. It was found that a path was formed, and as a result, leakage magnetic flux as shown by 6-1 and 6-2 in FIG. 3 was generated.

Furthermore, the magnetic fluxes 7-1 to 7-5 in FIG. 3 are invalid magnetic fluxes that do not contribute to the motor thrust because they form a magnetic path that short-passes without acting on the armature coil. It can be said that the magnetic flux is unfavorable in that it contributes to the magnetic saturation of the mover yoke 2 since it passes through the mover yoke 2. The leakage magnetic flux generated for this reason has various problems as described below with respect to the thin linear DC motor.

When they are mounted densely, a suction force is generated between adjacent motors, which makes mounting difficult.

When they are mounted densely, they may cause a magnetic noise source to the adjacent motor, and may cause a malfunction especially to magnetic sensors.

The magnetic field leakage cannot fully extract the power of the field magnet.

Since the field is large at the center of the yoke and small at the ends due to the imbalance of the leakage magnetic flux, the yoke is distorted so as to be recessed at the center and there is a risk of contact with the coil.

It is an object of the present invention to provide a linear DC motor having an inexpensive and easy structure for preventing magnetic flux leakage, which is one of the problems when thinning a conventional linear motor.

[Means for Solving the Problems]

According to this invention, a mover having a field magnet with at least two poles, a coil arranged along the traveling direction of the mover, and a magnetic sensor for detecting a magnetic field applied to the coil are provided. In a movable magnet type linear motor consisting of a stator that slidably supports a field magnet, one pole of the field magnet has two equal widths obtained by dividing the field magnet having the same width as the field magnets of the remaining poles into two. The field magnet halves are arranged such that different poles are alternately arranged at both ends of the remaining field magnets, and the field magnet halves have field magnets having at least two poles. A mover is configured.

Furthermore, the field magnet having at least one pole and the two field magnet halves at both ends are not in close contact with each other, and there is at least a distance of approximately equal to the air gap between the field magnet surface and the stator yoke. The width of the pole field magnet and the two field magnet halves at both ends are reduced.

[Embodiment] FIG. 1 shows a mover portion in an embodiment of the present invention. The stator is the same as the conventional one shown in FIG. In this embodiment, one of the four-pole field magnets having the same width is used.
Two field magnet halves 3-1-1 and 3 with the same pole width
-1-2 divided into two, and these field magnet half bodies 3-1
-1, 3-1-2 constitute a one-pole field magnet. And these field magnet halves 3-1-1, 3-
Field magnets of the same width with 3 poles separated from 1-2 3-
The mover is arranged at both ends of 2, 3-3, and 3-4, and has a 4-pole field magnet in which different poles are alternately arranged in the moving direction of the mover. Also, the center-to-center spacing of the intermediate three-pole field magnets 3-2, 3-3, 3-4 is Pm as in the conventional example of FIG. 2, but their width is made smaller than that of the conventional example. A space 8 is formed between adjacent field magnets. The two field magnet halves 3-1-1, 3-
Since 1-2 is half the width of a field magnet of any one pole, the center position before dividing into two is at the position of the outer end of them, and this is assumed to be a virtual center position and adjacent to these halves. If the center-to-center spacing between the field magnets 3-2 and 3-4 is Pm, the spacing 8 having the same width is formed between them. The size of the space 8 is made substantially equal to the air gap between the surface of the field magnet and the yoke on the stator side.

According to the embodiment shown in FIG. 1, as compared with FIG. 3, the leakage magnetic fluxes 6-1 and 6-2 at the ends and the ineffective magnetic fluxes 7-1 to 7-5 that do not act on the armature coil. Can be eliminated or eliminated altogether.

Next, specific numerical examples will be described with reference to FIGS.

In FIG. 2, each field magnet 3-1 to 3-4 has a width of 12 mm.
The total width of the mover having a structure in which four poles of -4 are mounted on the mover yoke 2 without a gap as shown in the figure is 48 mm. On the other hand, the armature coils 4 are arranged on the coil substrate 5 on the stator yoke 1 along the moving direction of the mover at intervals of 4/3 Pm, that is, 16 mm. The thickness of each part is 1 stator yoke 1.5mm, 9 coil substrate 0.4mm, 4 armature coil 2.0mm, gap between coil and magnet 0.5mm, field magnet 2.1mm, this mover yoke 1.5mm The total thickness is 8 mm. In the structure according to the present invention shown in FIG. 1, the thickness dimension and the material are exactly the same, but as shown in FIG. 1, the field magnet halves 3-1-1 and 3-1 at both ends are formed. -2 width is 5mm
The width of the three central magnets 3-2, 3-3, 3-4 is 10 mm, and the distance between the field magnets 8 and the distance between the field magnets and the field magnet halves are 8 mm. Is 2 mm
Is.

In this embodiment, the magnet is Neomax made by Sumitomo Special Metals and the yoke material is SS-41.

FIG. 3 shows the results of measuring the magnetic flux on the surface of the mover of A, B and C shown in FIG. 1 in the mover of the conventional type shown in FIG. 3 and the mover of the embodiment of the present invention shown in FIG. Table 1 shows a comparative table of both equations in FIG. Magnetic flux measuring instrument is Electronic Magnetic Industry Co., Ltd.
Gaussmeter GM-5225IV manufactured by K.K.

As shown in Table 1, in the case of the embodiment according to the present invention, the leakage magnetic flux was very small, the magnetic attraction force with other was almost unnoticeable, and there was no fear of magnetic noise to the other. Also, since the effective magnetic flux acting on the armature coil is almost unchanged, the motor power is almost the same as the conventional type, but the mover is lighter and the high-speed operability is rather improved by the size of the field magnet. It was

As described above, since the movable magnet type linear DC motor according to the present invention can reduce or eliminate the leakage magnetic flux when it is made thin, it is used in a narrow space not only in textile machines but also in head drive fields such as disk memories. It is very useful when

[Effect of device]

Since the movable magnet type linear DC motor according to the present invention is configured as described above, it is possible to greatly reduce or eliminate the leakage magnetic flux as compared with the conventional linear DC motor. As a result, conventionally, when a plurality of linear motors are densely arranged, for example, for driving a knitting needle of a flat knitting machine, an attractive force acts between the adjacent linear motors due to the leakage magnetic flux, which makes mounting very difficult. Or in a field where thinner magnetic flux is required to prevent the leakage magnetic flux from becoming a noise source to others, the problem is solved by solving such a problem. It is possible to utilize the movable magnet type linear DC motor.

[Brief description of drawings]

FIG. 1 is a sectional view of a mover of a movable magnet type linear DC motor shown in FIG. 2 and a magnetic path when the mover according to the present invention is improved, and FIG. Sectional view showing an example of a movable magnet type linear DC motor according to the method,
FIG. 3 is a diagram conceptually showing the magnetic path of the mover portion in FIG.

Claims (2)

[Scope of utility model registration request] 1. A movable element having a field magnet having at least two poles, a coil arranged along the traveling direction of the movable element, and a magnetic sensor for detecting a magnetic field applied to the coil. In a movable magnet type linear DC motor including a stator that slidably supports a mover, one pole of the field magnet has two field magnets having the same width as the field magnets of the remaining poles. The field magnet halves having the same width are arranged such that different poles are alternately arranged at both ends of the field magnets of the remaining poles, and the field magnet halves have at least two poles. A movable magnet type linear DC motor characterized in that a mover having a magnet is configured. 2. The field magnet and the two field magnet halves are not closely arranged, and there is a distance substantially equal to an air gap between the field magnet surface and the yoke on the stator side. 2. The movable magnet type linear DC motor according to claim 1, wherein widths of the field magnet and the two field magnet halves are reduced.