JPH04217855A - Permanent magnet linear drive motor - Google Patents

Abstract

PURPOSE: To obtain a linear drive motor which is efficient relatively compact and lightweight as compared with a conventional one. CONSTITUTION: The inventive permanent magnet linear motor comprises a fixed module 10 comprising several permanent magnets 12 arranged at a predetermined interval, and a moving module 18 comprising a pair or more of U-shaped electromagnets 20, 22. The permanent magnets are arranged while alternating N and S poles on a plane and spaced apart from an adjacent electromagnet by a distance equal to the distance between the permanent magnets arranged on the fixed module. Furthermore, the electromagnets are connected such that when one electromagnet is matched with the gap between two permanent magnets, the other electromagnet is matched with a third permanent magnet.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a linear motor,
In particular, it relates to a linear motor for opening and closing elevator doors.

0002

BACKGROUND OF THE INVENTION It is known to use linear motors to open and close elevator doors. For example, U.S. Patent No. 2,303,2, both of Fisher's patents,
No. 63 and No. 2,365,632 disclose linear motors for opening and closing elevator doors.

Each linear motor includes a linear stator having magnetic sections of equal length alternating with non-magnetic sections, and several electromagnets spaced apart so as to be movable longitudinally along the stator. , sequentially and sequentially energizing the electromagnets to move in one direction, or sequentially and reversely energizing the electromagnets to move in the opposite direction, in response to relative movement of those electromagnets. equipped with the means.

0004

The above-mentioned motor has the following drawbacks. That is, (1) the relay system for supplying power to the electromagnet is complex, difficult to handle, and heavy; Each electromagnet is powered so that it is driven for one-third of the time, but the remaining two-thirds of the time the electromagnet is passive, resulting in a low motor drive efficiency. As a result, only the electromagnet receiving power will work and must pull the other two electromagnets. Additionally, at least three electromagnets must be used to smoothly open and close the door, resulting in a fairly heavy and large motor.

Accordingly, it is an object of the present invention to provide an efficient permanent magnet linear drive motor.

Still another object of the present invention is to provide a linear drive motor that is relatively compact and lightweight.

[0007]

SUMMARY OF THE INVENTION A permanent magnet linear motor according to the present invention includes a first module formed from several aligned permanent magnets separated by gaps of fixed length;
A second module formed from one or more pairs of U-shaped electromagnets is provided. The permanent magnets are arranged in a plane with north and south poles alternating, and the electromagnets have parallel legs and are equal to the width of the gap between the permanent magnets arranged on the fixed module. It is separated from the adjacent electromagnet by the width. Further, the electromagnets are connected such that when one of the electromagnets is aligned with the gap between the two permanent magnets, the other is aligned with a third permanent magnet.

It further comprises means for detecting the position of one of the electromagnets with respect to the permanent magnet, and means for supplying electrical power to the electromagnets as a function of the position of the electromagnet, such that each electromagnet has the following characteristics:

(1) The first point when the electromagnet advances a certain distance beyond alignment with a permanent magnet, and the first point when the electromagnet reaches the same distance before aligning with the next permanent magnet. (2) no power between the third point and the second point as the electromagnet passes over the next permanent magnet; and (3) no power between the third point and the second point. has opposite polarity at the point.

According to another aspect of the invention, the linear drive motor of the invention includes a first module formed from several aligned permanent magnets separated by a gap of a fixed length; A second module formed from a letter-shaped electromagnet is provided. The permanent magnets are arranged in a plane with north and south poles alternating, and the electromagnets have parallel legs and are equal to the width of the gap between the permanent magnets arranged on the fixed module. It is separated from the adjacent electromagnet by the width. Further, the electromagnets are connected such that when one of the electromagnets is aligned with the gap between the two permanent magnets, the other is aligned with a third permanent magnet.

[0011] Each electromagnet also has (1) a first
and the second point when the electromagnet reaches the same distance before aligning with the next permanent magnet, (2
) no power between the third point and the second point as the electromagnet passes over the next permanent magnet; and (3) reverse polarity at the third point.

0012

The motor of the present invention is more efficient than prior art motors in which the permanent magnets exert attractive and repulsive forces to constantly drive the moving module. The electromagnetic force is
It acts on the two electromagnets at all times, except for a short time between the second and third moments, when one of the electromagnets is working.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Refer to FIGS. 1 and 2. The linear motor is
A series of stationary permanent magnets 12- held in place by a carrier bar 14 arranged in a plane and having a T-shaped cross section.
1, 12-2, 12-3, 12-4,... and a mobile module 18 formed by two rigidly mounted electromagnets 20, 22.
and a control means 21. The carrier bar is made of non-magnetic material and is fixed to the support 16. As one skilled in the art will readily understand, the control means 21 consists of an electric or electronic controller and a power source (not shown).

The north poles of the permanent magnets 12 are alternated vertically, as shown in FIG. Therefore, the first, third, fifth, etc. (not shown) magnets 12 have upward N poles;
The N poles of the second, fourth, sixth, etc. (not shown) magnets face downward. These magnets have a fixed length gap 24
separated by.

Each electromagnet 20, 22 consists of a U-shaped core with parallel legs 26, 27 attached to each other by a connecting portion 31. Their parallel legs overlap the carrier bar 14. The windings 28 , 29 are wound around the connecting part 31 and are adapted to be energized by the control means 21 . The electromagnet consists of two rods 2
0 and 32. The rods hold the electromagnets parallel at a distance so that when one electromagnet opposes a permanent magnet, the other aligns with the gap 24 separating the two magnets 12. Maintained.

The Hall effect probe 34 includes an electromagnet 20,
22 and communicates with the control means via a lead wire (not shown). The probe measures the magnetic field of the permanent magnet. The probe generates a proportional signal, according to which the control means control the windings 28 of the electromagnet.
A current is supplied to 29. This point will be explained in detail below with reference to FIGS. 3 to 7.

For purposes of explanation, it is assumed that movement module 18 is initially in the position shown in FIG. As shown in the figure, the top surface is the south pole and the bottom surface is the north pole.

In the initial position, permanent magnet 12-1 is detected by Hall effect probe 34. and,
A signal proportional to the measured magnetic field is provided to the control means 21. The control means is such that the upper leg of the electromagnet forms a south pole;
A current is supplied to the electromagnet 20 so that its lower leg forms the north pole. At the same time, its upper leg is the north pole and the lower leg is the south pole.
A current is supplied to the electromagnet 22 so as to serve as a pole. The like poles of electromagnet 20 and magnet 12-1 repel each other, thereby moving the module to the right. Also, the opposite polarity of electromagnet 22 and magnet 12-3 attract each other, thereby moving the module to the right.

Next, refer to FIGS. 8 to 13. Forces on the movement module are applied as shown. Figure 8 shows
The waveform of the current supplied to the electromagnet 20 by the control means 21 is shown. The current has a square wave and is assumed to be constant. The waveform of the current supplied to electromagnet 22 (not shown) is the same as that applied to electromagnet 20, but
The phase is shifted by the length of the magnet.

FIG. 9 is a diagram showing the amplitude of the repulsive force F1 generated from the magnetic field in the vicinity of two same poles (for example, 12-1 in FIG. 3) at each position d of the center of the electromagnet 20. On the other hand, FIG. 10 shows the distribution of the attractive force F2 generated by the magnet (for example, 12-2 in FIG. 3) following the moving direction.

FIG. 11 shows the resultant force F acting on the electromagnet 20.
The distribution of 1+F2 is shown.

Similarly, FIG. 12 shows the distribution of the resultant force F1'+F2' acting on the electromagnet 22.

Finally, FIG. 13 gives the total resultant force F acting on the moving module 18. Note that this force is never zero. Furthermore, as will be readily understood by those skilled in the art, by utilizing control means to provide a current with an appropriate current waveform, it is possible to minimize the fluctuations in the resultant force F in order to obtain a relatively constant driving force. can. As one skilled in the art will appreciate, the waveform of the current supplied to the electromagnet can be derived directly from the signal supplied by the probe as compared to the magnetic field distribution sensed by the Hall effect probe.

The movement module 18 operates as a result of the forces described above and illustrated in FIGS. 8-13. Next, reference is made to FIGS. 3 to 7. When the moving module 18 reaches the position shown in FIG.
At a distance d before alignment with 23, the power to this electromagnet is cut off by the control means. Powering the electromagnet 22 beyond this point is inefficient since the attractive force acting on the magnet 123 decreases and reaches zero just as it passes the opposing permanent magnet 123. Regardless of the current interruption to the electromagnet 22, the moving module 18 continues to move due to the repulsive and attractive electromagnetic forces between the permanent magnets 12 and 122 and the electromagnet 20, respectively.

The control means is configured such that the electromagnet 22 is connected to the permanent magnet 12.
The current is kept interrupted until the position shown in FIG. At this time, its polarity is reversed, that is, the upper leg is the S pole and the lower leg is the N pole.
Become the pole.

For the same reasons as before, namely, the attractive force between electromagnet 20 and magnet 122 and the repulsive force between electromagnet 22 and magnet 12-3, moving module 1
It can be seen that 8 moves to the right as before.

This movement causes the electromagnet 20 to move towards the permanent magnet 12.
Continue without change until reaching the position shown in FIG. 6, which is at a distance d before alignment with -2. Thereafter, the current to the electromagnet 20 is cut off by the control means 21. When electromagnet 20 reaches the position shown in FIG. 7, which is a distance d beyond alignment with permanent magnet 12-2, current is re-established. Module movement continues in this manner.

It goes without saying that if the polarity of the electromagnet legs is reversed with respect to the polarity shown in FIGS. 3 to 7, movement in the opposite direction will occur.

The linear motor of the present invention has many advantages and can be used in many applications. The second and third uses will be explained later using examples.

By controlling the magnetizing current or driving force, the speed of movement of the moving module can be adjusted. This control is performed automatically by the control means by comparing the magnetic charge profile obtained by the Hall effect probe with a stored representative profile.

When the moving module is moving backwards, a braking force is produced by the reversal of the magnetizing current. Movement in the magnetic field of the permanent magnet causes the electromagnets to connect to the terminals of their windings.
Generates a transmissive electromotive force dψ/dt. ψ is the magnetic flux obtained by the number of windings of the electromagnet.

[0032] Via the probe, the control means counts the permanent magnets during movement and automatically controls the stopping of the movement module and holds it in position with precision. For example, when electromagnet 22 reaches a position opposite the nth permanent magnet (not shown) at the point where the module is programmed to stop, the current to electromagnet 22 is maintained and the current to electromagnet 20 is is blocked.

Any movement caused by an external force on one side or the other of the equilibrium position creates a horizontal component of the electromagnetic force that again places the poles of electromagnet 22 against the nth permanent magnet pole, so that the module After that, a stable equilibrium state is reached.

Obviously, the accuracy of the module placement is
Directly related to the spacing or pitch of the permanent magnets. In the case of the module with two electromagnets described so far, the accuracy is half a pitch, since the electromagnets can be stopped either against the permanent magnet or against the gap 24.

In an interesting embodiment, it is possible to construct the equivalent of a vernier by adding several further modules and moving their electromagnets by different small steps.

The linear motor according to the present invention can be used to open and close a sliding door. In this case, a carrier bar 14, which holds the permanent magnets in position, is fixed to a door lintel (not shown). Electromagnets are fixed to the door carriage (not shown) and their number is increased depending on the weight of the door being driven.

The linear motor according to the invention can also be used to drive a counterweight (not shown). In that case, the principle is the same as in the application described above, only a greater force is required. By increasing the number of moving modules together with the carrier bar 14, the output of the motor can be sufficiently increased. These bars are fixed end to end and can act as guides.

[0038]

The present invention provides a linear drive motor that is more efficient, relatively compact, and lightweight compared to conventional motors.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a preferred embodiment of a linear motor according to the present invention.

FIG. 2 is a perspective view of several permanent magnets arranged in the fixed part of the linear motor of FIG. 1;

3 is a schematic diagram of successive positions of the movable part of the linear motor of FIG. 1; FIG.

4 is a schematic diagram of successive positions of the movable part of the linear motor of FIG. 1; FIG.

5 is a schematic diagram of successive positions of the movable part of the linear motor of FIG. 1; FIG.

6 is a schematic diagram of successive positions of the movable part of the linear motor of FIG. 1; FIG.

7 is a schematic diagram of successive positions of the movable part of the linear motor of FIG. 1; FIG.

8 is an explanatory diagram of forces acting on the permanent magnets of the linear motor of FIG. 1. FIG.

9 is an explanatory diagram of forces acting on the permanent magnets of the linear motor of FIG. 1. FIG.

10 is an explanatory diagram of the force acting on the permanent magnet of the linear motor of FIG. 1. FIG.

11 is an explanatory diagram of forces acting on the permanent magnets of the linear motor of FIG. 1. FIG.

12 is an explanatory diagram of forces acting on the permanent magnets of the linear motor of FIG. 1. FIG.

13 is an explanatory diagram of forces acting on the permanent magnets of the linear motor of FIG. 1. FIG.

[Explanation of symbols]

10 Fixed module 12 Permanent magnet 18 Movement module 20, 22 Electromagnet 21 Control means 34 Probe

Claims (4)

[Claims] 1. A linear first module formed of several aligned permanent magnets separated by a gap of a constant length and having alternating north and south poles, and a gap between the permanent magnets. a second module formed from one or more pairs of the above U-shaped electromagnets having a width equal to the width of the U-shaped electromagnets and having parallel legs disposed on each side of the first module;
A connection length such that when one of the electromagnets is aligned with the gap between the two permanent magnets, the other opposes a third permanent magnet, the electromagnets of each pair are rigidly connected, and each electromagnet (1) the first point when the electromagnet advances a certain distance beyond alignment with a permanent magnet, and the first point when the electromagnet reaches the same distance before aligning with the next permanent magnet. (2) no power between the third point and the second point as the electromagnet passes over the next permanent magnet; and (3) no power between the third point and the second point. A linear drive motor characterized in that it has reverse polarity at points. 2. A linear first module formed of several aligned permanent magnets separated by a gap of a constant length and having alternating north and south poles; and a gap between the permanent magnets. a second module formed from a pair or more of the U-shaped electromagnets having a width equal to the width of the U-shaped electromagnets and having parallel legs disposed on each side of the first module; each pair of electromagnets is firmly connected by a connection length such that one opposes a third permanent magnet when is aligned with the gap between the two permanent magnets;
further means for transmitting a signal representative of the position of the electromagnet with respect to the permanent magnet; and control means for receiving said signal and controlling the power supply to said electromagnet as a function of said signal, such that each said electromagnet has the following characteristics: A linear drive motor comprising: (1) The first point when the electromagnet advances a certain distance beyond alignment with a permanent magnet, and the second point when the electromagnet reaches the same distance before aligning with the next permanent magnet. (2) the third polarity when the electromagnet crosses the next permanent magnet mentioned above;
and (3) reverse polarity at the third point. 3. A linear drive motor according to claim 2, characterized in that said signal sending means consists of a Hall effect probe fixed to one of the electromagnets. 4. The linear drive motor according to claim 2, further comprising a nonmagnetic carrier bar having a T-shaped cross section for supporting the electromagnet.