JPH0412784Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention is a linear induction motor (hereinafter referred to as
This paper relates to an improvement plan for the primary stator that constitutes the LIM (abbreviated as LIM).

[Conventional technology]

The primary stator of a LIM generally consists of an iron core made up of a number of laminated comb-like iron plates, as shown in Figure 2.
The single-phase or polyphase winding 3 is inserted into the slot 2 (this slot exists at a constant pitch in the longitudinal direction of the iron core).
It is said that the structure has a

However, in the illustrated stator, since the opening of the slot 2 is large, the magnetic field generated between the secondary conductor (reaction plate) 4, which is made by laminating a conductor such as aluminum on an iron plate, is caused by the teeth 5 of the iron core. The magnetic field becomes stronger in the region , and the spatial distribution of the magnetic field changes as shown in the lower part of Figure 2. Since the magnetic field that has changed in this way is amplitude-modulated with a period equal to the pole pitch, a force is generated that cancels the thrust of the LIM,
Motor output (=thrust) decreases.

Here, the thrust of the LIM is approximately proportional to the inverse square of the gap between the primary stator and the secondary conductor. Therefore, in order to increase the thrust, the above gap should be made as small as possible. However, the smaller the gap, the more remarkable the above-mentioned thrust reduction phenomenon becomes.

Therefore, as a countermeasure to this problem, as shown in Fig. 3, a protrusion 6 is formed at the tip of the tooth 5 of the iron core 1 to narrow the opening width of the slot 2 to alleviate changes in the magnetic field. .

However, when protrusions are provided on the tips of the iron core teeth, it is not possible to adopt an efficient manufacturing method of coiling the winding 3 in advance into the required shape and fitting it together, and it is also difficult to insert the conductor into the slot. If the wire is directly wound to form a winding wire, the workability deteriorates and the winding machine becomes complicated.

Therefore, Japanese Patent Publication No. 58-49102 proposes covering the surface on which the slot is formed with a thin plate of magnetic material. According to this structure, since the thin plate moderates the magnetic flux distribution between the teeth of the iron core, it is not necessary to shape the teeth of the iron core as shown in FIG. 3, and the above-mentioned problems associated with manufacturing are eliminated.

[Problem that the invention attempts to solve]

The technology disclosed in the above-mentioned Japanese Patent Publication No. 58-49102 is as follows:
Since a thin plate spanning the entire length of the iron core is attached to the slot forming surface, eddy currents occur in the magnetic thin plate, resulting in eddy current loss. Therefore, a method has been adopted to reduce eddy current loss by forming slits in the thin plate.
This does not eliminate the eddy current loss, and even if the plates are thin, the problem of magnetic flux leakage between adjacent magnetic poles through the thin plates remains, so the effect of improving the motor output is reduced accordingly.

Furthermore, since the distance (span) between the fixed parts of the thin plate is long, it is possible that the thin plate vibrates and generates vibration noise.

In addition, Utility Model Publication No. 54-90615 or Special Publication No.
Publication No. 54-159620 discloses a technique in which a wedge is locked at the entrance of a slot and the opening of the slot is closed with this wedge. Magnetic flux leakage occurs between magnetic poles and motor output does not increase.

The present invention has been made to solve this problem.

[Means for solving problems]

The LIM primary stator of the present invention, which eliminates the above problems, has two slots in the iron core 1, as shown in Figure 1.
Dovetail-like locking grooves 7 facing each other with the slot 2 in between are provided across the entire width of the iron core at the tips of the teeth 5 formed in between, and after the winding 3 is inserted into the slot, the iron core A central portion 8a having a width _W1 smaller than the slot width W in the longitudinal direction is formed of a non-magnetic material such as FRP (fiber-reinforced plastic), non-reinforced plastic, ceramics, stainless steel, etc., and both side portions are brought into contact with the iron core. It is characterized in that a wedge 8, in which 8b and 8b are made of a magnetic material such as iron, is inserted between the opposing locking grooves 7 and 7.

In other words, the tooth tip width of the iron core is increased, and at the same time, eddy current loss,
The effect of preventing magnetic flux leakage between adjacent magnetic poles (eddy current loss and magnetic flux leakage are caused by forming the central part of the wedge with a non-magnetic material and breaking the electromagnetic connection between both sides). By removably attaching a wedge to the slot opening, this design minimizes changes in the spatial magnetic field caused by the strut shape without deteriorating the ease of installing the winding, and prevents a drop in thrust. be.

The edges 8b, 8b of the wedge 8 are inserted into the groove 7 in a shape that corresponds to the shape of the groove 7, and the edges are inserted into the groove 7 slightly tightly to prevent the wedge from slipping out. .

In addition to adhering the magnetic material and non-magnetic material of the wedge 8, if both are metal, they can be integrated by crimping, welding, etc., or the wedge can be cut out from materials that have been laminated together in advance. You can also use the method mentioned above.

〔effect〕

In the primary stator of the present invention described above, the tooth width of the iron core is expanded at the tooth tips by the magnetic materials on both sides of the wedge, so changes in the spatial distribution of the magnetic field can be suppressed to a small level. In addition, since the wedge has the electromagnetic connection cut off between both sides, eddy current loss and magnetic flux leakage between adjacent magnetic poles are also prevented, and as a result, the reduction in thrust of the LIM is smaller than before. Furthermore, since the wedges are fixed in each slot, there is no need to worry about the wedges vibrating and causing noise.

In addition, the wedge is removably inserted into the locking groove on the tips of the teeth facing each other with the slot in between, and when it is removed, the slot width remains constant from the tip to the back.
The winding can also be easily attached.

In addition, the wedge also provides the effect of holding the windings.
It also becomes easier to fix the winding.

[Brief explanation of drawings]

Fig. 1 is a partially exploded perspective view of the primary stator of the present invention, and Fig. 2 is a side view showing a LIM employing a conventional primary stator, including a spatial distribution diagram of the magnetic field. , FIG. 3 is a cross-sectional view of an iron core conventionally employed to alleviate changes in the magnetic field. 1... Iron core, 2... Slot, 3... Winding wire, 5
. . . Teeth, 7 . . . Locking groove, 8 . . . Wedge, 8 a . . . Central portion made of non-magnetic material, 8 b .

Claims (1)

[Scope of utility model registration request] In the primary stator of a linear induction motor, which is composed of a comb-shaped iron core with slots provided at fixed pitches in the longitudinal direction, and a winding inserted into the slots, the tips of the teeth of the iron core are Opposing locking grooves are provided across the entire width of the iron core with the slot in between, and after the winding is inserted into the slot, the central portion, which is narrower than the slot width in the longitudinal direction of the iron core, is made of non-magnetic material. A primary stator for a linear induction motor, characterized in that a wedge whose both sides contacting the iron core are formed of a magnetic material is inserted between the opposing locking grooves.