JPH0721104Y2 - Linear synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a linear synchronous motor, which is a linear electromagnetic actuator and is controlled at a variable speed by a variable frequency power source, and more particularly to a structure of a permanent magnet field portion thereof.

[Conventional technology]

FIG. 3 is a side view of a conventional linear synchronous motor as seen from the direction of field movement, and FIG. 4 is a sectional view taken along the line AA of FIG. In the figure, a truck 10 having wheels 11 guided by the rail 12 is placed on a rail 12 laid on a track 13, and the truck 10 is made of a non-magnetic material whose upper end is fixed to its lower surface. A permanent magnet field 4 of a linear synchronous motor having a length 1 and including a support 6 and a plurality of plate-shaped permanent magnets 5A, 5B, 5C, 5D etc. 5 fixed to the support 6 is attached. , A plurality of permanent magnets are fixed to the support 6 while maintaining a predetermined pole pitch so that N poles and S poles are alternately arranged along the orbit.

On the other hand, on the track 13 side, a pair of armatures 1A, 1B is attached so as to hold the air gap length g between the permanent magnet 5 and the field magnet 4 and the armatures 1A, 1B have a length L, a magnetic field. Iron plate stacking thickness H
And an armature winding 3 formed of a multi-phase AC winding wound in a coil storage groove formed along the track in a predetermined phase order and pole order. By connecting the winding 3 to a variable voltage and variable frequency power source such as an inverter (not shown) and controlling the current and frequency supplied to the armature winding, the thrust of the linear synchronous motor and the moving speed of the field 4 can be controlled. Therefore, a linear electromagnetic actuator is formed which causes the carriage 10 to reciprocate along the rail 12 at a desired thrust and speed.

[Problems to be solved by the device]

By energizing the armature winding from a power source such as an inverter, an electromagnetic force is generated between the armature winding and the field at a position facing the field 4 having a length l, and the bogie in the figure. Ten
As a result, the back electromotive force e is generated in the armature winding at the position facing the field by the field moving at the synchronous speed. The product of this counter electromotive force e and the current I flowing from the power supply to the primary winding becomes the effective power for generating the electromagnetic force that drives the truck. On the other hand, a magnetic field is generated in the air gap having a gap length G between the armatures 1A and 1B by the current I flowing through the armature windings located in the sections LA and LB not facing the field. When viewed from the power source, this magnetic field acts as an exciting reactance Xm represented by the following formula, and requests reactive power to the power source.

Where Kw: coefficient determined by armature winding, Vs: synchronous speed (m /
s] H: Primary iron core product thickness of linear synchronous motor [m] τ: Pole pitch of linear synchronous motor [m] In the above equation, excitation reactance Xm is the ratio of armature to field length L / l, linear It increases in proportion to the stack thickness H of the armature core determined by the output of the synchronous motor, the synchronous speed Vs, etc., and decreases in inverse proportion to the ratio G / τ of the pole pitch τ and the air gap length G. In a linear synchronous motor that requires an expensive power supply device such as an inverter, the cost of the power supply device has a high weight on the economy of the entire device, and therefore reduction of reactive power is important.

It is known that the conventional linear synchronous motor has an armature length L of about 1 m to 3 m and an armature length L of about 5 to 10 times the field length l. Therefore, the pole pitch τ is also several cm
And small. Further, there is a manufacturing limit on the thickness t in the magnetization direction of ferrite magnets, rare earth magnets, etc. used as the permanent magnets 5, and the thickness t of currently available permanent magnets is 20 mm or less. As a result, the air gap length G between the pair of armatures is about 30 mm, and the value of G / τ that has a large effect on the excitation reactance Xm is inevitably large. Reduction was not too much of a problem.

However, due to advances in technology for applying linear synchronous motors to actuators, linear synchronous motors with longer armature lengths, such as large actuators with armature lengths of 10m to 30m, have been sought after. Since it is necessary to increase the pole pitch τ of the linear synchronous motor to a dozen cm, the gap length G between the pair of armatures must be increased.
If the G / τ value is not increased, the exciting reactance Xm increases and the reactive power increases, resulting in a large variable voltage,
Since a variable frequency power source is required, there arises a problem that the economical efficiency of the linear electromagnetic actuator is impaired. In order to increase the air gap length G, the thickness of the permanent magnet field in the magnetization direction is increased in proportion to this, and the air gap length g between the permanent magnet and the armature is set to a value equal to that of the conventional device.
Although it is necessary to maintain the thickness to about mm to prevent the thrust from decreasing, there is a problem that the thickness of the permanent magnet cannot be increased to a desired dimension due to the above-mentioned manufacturing restrictions.
As a method of solving this, a method of forming a permanent magnet field by bonding a plurality of permanent magnets with a thickness of 20 mm or less can be considered, but it is economically disadvantageous because an expensive permanent magnet material is used more than necessary. It has the drawback of inviting.

An object of the present invention is to obtain a large-sized linear synchronous motor having a small excitation reactance and a long armature length by using an appropriate amount of a readily available permanent magnet material.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, according to the present invention, a permanent magnet field supported by a carriage guided by a track via a support body, and this permanent magnet field is provided with air gaps on both sides thereof. A pair of armatures supported on the track side so as to be sandwiched, in which a support made of a non-magnetic material and a plurality of ferromagnets intermittently supported at a predetermined pole pitch are supported by the support. And a pair of permanent magnets fixed to both sides of the plurality of ferromagnetic bodies so that magnetic pole surfaces of different polarities face the pair of armatures, and the polarities of the permanent magnets adjacent to each other are A permanent magnet field magnetized so as to be alternately inverted is provided.

[Action]

In the above means, a ferromagnetic material such as an iron material supported by a support is used as a spacing material, and permanent magnets of a plate material are attached to both sides of the spacing material. By forming the permanent magnet field that serves as a pole, the thickness of the two permanent magnets stacked is the thickness required to create a predetermined magnetic field in the air gap length g, and therefore a commercially available permanent magnet Since a magnetic material can be used and an arbitrary gap length G can be obtained simply by changing the thickness of an inexpensive ferromagnetic material such as an iron material, it is possible to take a large G / τ value without incurring any economic disadvantage. A large linear synchronous motor having a long armature core length can be obtained without increasing the excitation reactance, and an increase in power supply capacity can be prevented.

In addition, by using a permanent magnet field with a structure in which a ferromagnetic material with a large magnetic permeability is inserted between the permanent magnets, the magnetomotive force consumed by this ferromagnetic material is greater than that consumed by the entire magnetic circuit. It is very small and has almost no influence on the thrust of the linear synchronous motor.

〔Example〕

 The present invention will be described below based on embodiments.

FIG. 1 is a side view showing a linear synchronous motor as an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line BB in FIG. In the figure, the permanent magnet field 20 is fixed to the lower surface of the carriage 10 by a support 6 made of a non-magnetic material, and a ferromagnetic body 21 made of an iron material or the like holds a predetermined pole pitch on the support 6. A plurality of plate-shaped permanent magnets 22 and 23 are provided on both sides of the plate-shaped ferromagnetic material 21 intermittently.
Are fixed by a thermosetting adhesive such as an epoxy resin, and the polarities of the pair of permanent magnets 22 and 23 facing each other with the air gap g held between the pair of armatures 1A and 1B are the N pole and the S pole. , And the polarities of the permanent magnet fields adjacent to each other are alternately inverted.

In the linear synchronous motor configured as described above, a pair of armatures 1A is provided in order to prevent an increase in excitation reactance Xm caused by an increase in the length L of the armatures 1A and 1B and an accompanying increase in no-load loss. In order to increase the air gap length G between 1 and 1B, by increasing the thickness d of the ferromagnetic material 21 made of an inexpensive iron material, the ferromagnetic material 21 functions as a spacing material having a large magnetic permeability and the magnetomotive force is increased. It is possible to increase the thickness T of the permanent magnet field 20 with almost no loss. In addition, the thickness of the plate-shaped permanent magnets 22 and 23 is 2t.
Since the thickness required to generate a desired magnetic field in the gap with the armature is g, it is possible to use a plate-shaped permanent magnet of 20 mm or less determined by manufacturing restrictions. The amount of expensive permanent magnet material used can be suppressed to the necessary minimum. Although the pole pitch τ also increases with the increase in size of the linear synchronous motor, the gap length G can be easily increased, so that the G / τ value can be increased to the same level as that of the conventional small-sized machine. It is possible to prevent an increase in excitation reactance due to an increase in size and obtain a linear synchronous motor with little no-load loss.

[Effect of device]

As described above, this invention comprises the permanent magnet field of the linear synchronous motor as a ferromagnetic body supported by a non-magnetic support body and a pair of plate-shaped permanent magnets fixed to both surfaces thereof. As a result, the ferromagnetic material functions as a spacer having a high magnetic permeability, and easily and inexpensively increases the thickness of the permanent magnet field in the magnetization direction without loss of magnetomotive force or increase in the thickness of the permanent magnet. It is possible to increase the output of linear synchronous motors and the lengthening of armature iron cores, which is caused by the restrictions on the thickness of permanent magnet materials and the use of thin permanent magnets, which were problems in the prior art. It is possible to easily obtain the G / τ value corresponding to the size increase such as lengthening of the armature core by eliminating the economic disadvantage, and therefore the reactive power is small and the expensive variable voltage and variable frequency power supply capacity are also small. The linear synchronous motor can be provided economically and advantageously. In addition, because a large linear synchronous motor can be provided economically,
It can contribute to the increase in size of the linear electromagnetic actuator.

[Brief description of drawings]

1 is a side view showing a linear synchronous motor as an embodiment of the present invention, FIG. 2 is a sectional view taken along the line BB in FIG. 1, and FIG. 3 is a side view showing a conventional linear synchronous motor. FIG. 4 is a sectional view taken along the line AA in FIG. 1A, 1B ... armature, 2 ... armature core, 3 ... armature winding, 4,20 ... permanent magnet field, 5,22,23 ... permanent magnet, 6
...... Support, 21 ...... Ferromagnetic material, 10 ...... Truck, 12 ...... Rail, L ...... Armature iron core length, l ...... (Effective) length of permanent magnet field, G, g ... ... air gap length, T ... thickness of permanent magnet field, t ... thickness of permanent magnet, d ... thickness of ferromagnetic material.

Claims (1)

[Scope of utility model registration request] 1. A permanent magnet field supported by a carriage guided on a track via a support, and a pair supported on the track side so as to sandwich the permanent magnet field with air gaps on both sides thereof. In a pair of armatures, a support body made of a non-magnetic material, a plurality of ferromagnetic bodies that are intermittently supported by the support body while holding a predetermined pole pitch. The permanent magnets are fixed to the opposite surfaces of the plurality of ferromagnetic bodies in pairs so that the magnetic pole surfaces having different polarities face each other. The permanent magnets adjacent to each other are magnetized so that the polarities thereof are alternately inverted. A linear synchronous motor characterized by comprising a permanent magnet field.