JPS60197153A - Brushless linear motor - Google Patents

Abstract

PURPOSE:To reduce the variation in the speed by gradually increasing an air gap between a movable element and a stator at the positions in the same direction as the moving direction of the element, thereby decreasing the reverse attracting force. CONSTITUTION:A movable element 1 of a brushless linear motor is composed of magnetic materials having a pitch P1, and a coil 4 is wound on one tooth 3 of a stator 2. A magnet is formed on the side of the core of the stator 2, a magnetic flux from the magnet is emitted through a stator core 3, teeth 3 and a main gap to the element 1, and returned to the magnet. Thus, the element 1 is attracted and repelled by poles P1-P9 formed in the stator 2, the permanent magnet and a coil 4 to move in the direction of an arrow as shown. In this case, the poles P4-P6, P7-P9 increases the air gap distance l2 to the teeth of the element 1 in the direction that the element 1 moves. Thus, reverse torque can be reduced.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a gap between a stator and a movable element for a brushless linear motor, and particularly relates to a brushless linear motor suitable for reducing reverse torque when the movable element is separated from the magnetic poles of the stator. Regarding the structure of a linear motor.

[Background of the invention]

However, there is no conventional example in which the movable element of the near motor is ejected from the stator as in the present invention.

I will explain the drawbacks of this kind of thing. The stator 2 shown in FIG. 1 is provided with N magnetic poles P1 to PN.

The mover 1 moves in the direction of the arrow shown in the figure due to the attraction or repulsion of the magnetic poles P1 to PN of the stator 2, but when the mover 1 reaches the position shown by the broken line in the figure (in other words, it is launched) (When) Excitation of the movable element 1 from the stator 2 is stopped. Since the magnetic pole PN is constantly excited by a permanent magnet provided on the stator 2, the mover 1 has the disadvantage that the speed of the mover 1 is fluctuated by the attraction force exerted by the magnetic pole PN in the direction opposite to the direction of movement. .

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a brushless linear motor that reduces reverse torque when the movable element moves out of the excitation zone and does not cause speed ripples to the movable element. .

[Summary of the invention]

In order to achieve the above object, the present invention gradually increases the gap between the movable element and the stator at each position in the same direction as the moving direction of the movable element, thereby reducing the reverse attraction force that causes speed fluctuations applied to the movable element. This is intended to reduce speed fluctuations in the moving direction of the mover.

[Embodiments of the invention]

The operating principle of the present invention will be explained below with reference to the drawings. Second
3 are diagrams showing the basic structure of the present invention. The mover 1 is made of a magnetic material with a pitch of P, and the pitch of approximately 1/2 of the pitch P reduces the magnetic resistance between the mover and the stator, and the remaining 1/2 P + The pinch is made of a material with high magnetic resistance or configured to widen the gap. In the stator 2, one coil 4 is wound around one tooth 3. Then, one tooth 3 and the coil 4 form a coil for each phase and each pole. The pitch P2 of the teeth 3, ie, the phase between adjacent coils, is arranged so as to follow equation (1).

In equation (1), m is the number of phases of the motor. for example,
In the case of three phases, it can be 2Pl/3. A magnet 5 is provided on the side surface of the stator core 14, as shown in FIG. The magnetic flux 11 of the magnet 5 flows as shown by the broken line. That is, the magnetic flux emitted from the magnet 5 enters the stator core 14, reaches the teeth 3, passes through the main gap 7, and reaches the mover 1.
Return magnetic material9. Via the return gap 8, the yoke 10.
6 and returns to magnet 5. The role of the magnet 5 is to provide magnetizing force between the mover and the stator teeth. Therefore, the present invention can be realized without the structure shown in FIG.

Since the magnet 5 applies a constant magnetizing force between the stator teeth 3 and the mover 1, the magnetic flux in the main gap between the stator teeth and the mover changes as the mover moves. That is, the magnetic resistance of the main gap changes between the - position shown in FIG. 4 and the position shown in FIG. Fourth
The figure shows a case where the movable tooth IA and the tooth portion 3 coincide, and in this case, the magnetic flux of the magnet flowing through one coil 4 is the largest. FIG. 6 shows a case where the movable element and the stator are moved at a constant relative speed, and the magnetic flux flowing through the coil changes as shown by a curve 11. Point 0 in FIG. 6 corresponds to the position in FIG. 4, and point D corresponds to the position in FIG. Since the magnetic flux entering one coil changes like the song $11, coil 4
, an internal induced voltage as shown by curve 12 will be generated.

[Embodiments of the invention]

The operating principle of the brushless linear motor has been explained above.

An embodiment of the present invention will be described below with reference to FIGS. 7 and 8. In this case, nine magnetic poles will be explained.

FIG. 7 shows a cross-sectional view of a three-phase brushless linear motor, which is an example of the present invention, in a plane parallel to the moving direction of the movable element.

The mover 1 includes magnetic poles Pl to P9 . provided within the stator 2 . It moves in the direction of the arrow shown in FIG. 7 under the attraction or repulsion of a permanent magnet (not shown) and the coil 4. In the conventional example, the gap Ω between the magnetic poles P1 to PN and the teeth of the movable element 1 is constant, and exhibits speed fluctuations as shown in graph (1) shown in FIG. The present invention provides magnetic poles P4 to P6. P7 to P9 are mover 1
The magnetic poles P4 to P6 and P7 to
In order to widen the gap distance Q2 between P9 and the tooth of mover l,
If the number of turns of the coil 4 is kept constant by determining the distance of the air gap so that the attraction force from the magnetic pole P9 does not become a problem even when the mover 1 is located outside the mover excitation zone, the number of turns of the coil 4 can be maintained as shown in Fig. 3. It is expressed as graph (2). However, since the magnetic flux density decreases by widening the air gap, the final value cannot be expressed as shown in graph (1) of the conventional example. Therefore, as shown in FIG. 7, magnetic poles P4 to P6. The graph shown in FIG.
A speed fluctuation curve with respect to time t as shown in 3) can be obtained.

Although the above description has been made using nine magnetic poles, any number of magnetic poles may be used. However, in the case of three phases, the number of magnetic poles used is preferably a multiple of three.

Therefore, the present invention has the effect of extremely minimizing the reverse torque generated when the mover 1 comes off the magnetic pole P9 provided in the stator 2, thereby achieving maximum performance and minimizing speed fluctuations. be.

〔Effect of the invention〕

According to the present invention, there is an effect of transporting the movable element at a stable speed by reducing the reverse torque that cancels out the force in the advancing direction generated at the ends of the magnetic poles of the stator.

[Brief explanation of the drawing]

Figures 1, 2, and 7 are cross-sectional views of the brushless linear motor in a plane parallel to the moving direction of the movable element; Figure 5 is an enlarged sectional view of a plane parallel to the moving direction of the movable element of the brushless linear motor, Figure 6 is a phase curve diagram of magnetic flux, induced voltage, and current, and Figure 8 is a time-speed fluctuation curve diagram. show. l...Mover, 2...Stator, 3...Teeth, 4...
・Coil, 5... Magnet, 11... Magnetic flux change, 12.
...Induced voltage, 2nd day, 3rd eye, 5cL 1(4))l) 6th day

Claims (1)

[Scope of Claims] 1. A movable element having a plurality of uneven magnetic pole teeth made of a magnetic material at a constant pitch in the longitudinal direction, and a magnetic material facing the movable element with a slight air gap. has a stator;
A brushless linear motor configured such that a movable element is excited by a permanent magnet provided in the stator, characterized in that the gap distance between the stator and the movable element is gradually increased depending on the position in the longitudinal direction. motor. 2. The brushless linear motor according to claim 1, wherein the gap distance between the movable element and the stator is gradually widened in the same direction as the moving direction of the movable element used at that time. 3. In claim 1, the movable element is accelerated and launched at a certain position of the magnetic pole of the stator, and the gap distance between the stator and the movable element gradually increases in the same direction as the moving direction of the movable element. A brushless linear motor characterized by: