JPH0471359A - Moving magnet type dc brushless linear motor - Google Patents

Abstract

PURPOSE:To increase maximum thrust while lightening the weight of a needle and to obtain large acceleration by setting the width of a main magnet for drive in length of twice as large as the width of a coil piece. CONSTITUTION:Coils 2 and Hall elements 3 for detecting a magnetic pole are arranged onto a stator yoke 1. The width of a coil piece 4 contributing to thrust is represented by (d), the first and second coils are positioned without clearance, the second and third coils are arranged at the interval of 2d, and the coils are disposed by the repetition. Main magnets 6 and sub-magnets 7 for detecting the magnetic pole are arranged on a needle yoke 5, and the width of the main magnets 6 is represented by 2d, and the main magnets are positioned without clearance respectively. Each Hall element 3 is disposed so as to able to accurately detect the change of the magnetic pole to the coil 1 of the main magnets 2 by the sub-magnets 7 oppositely faced to the Hall elements 3 for detecting the magnetic pole, and the width of each sub-magnet is determined in response to the locations of the Hall elements 3. Accordingly, a needle is lightened, and large acceleration can be acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a movable magnet DC brushless linear motor suitable for a device for driving a plurality of motors, for example, a linear motor for driving needles in a flat knitting machine.

[Prior Art] FIGS. 7 to 9 show a conventionally known 120-degree energizing type linear motor.

In the conceptual diagram of the linear motor shown in Fig. 7, 1 is a stator yoke, 2 is a coil, 3 is a Hall element for magnetic pole detection, and 4
1 is a coil piece of the coil 2 that contributes to the thrust, 5 is a movable yoke, 6 is a main magnet, and 7 is a sub magnet for magnetic pole detection. Further, C indicates the width of the coil piece 4 that contributes to thrust among the coils 2 placed on the stator yoke 1. The total width of coil 2 is 3
c, and each coil is arranged with a gap C between them. The magnetic pole detection Hall element 3 is placed at the right end of each coil for the first to third coils counting from the left side in FIG. 7, and is placed at the left end of each coil for the fourth to sixth coils.

The width of the main magnet 6 placed on the mover yoke 5 is 3c,
The gap between each main magnet 6 is zero. Similarly, the width of the magnetic pole detection sub-magnet 7 is also 3c, and each sub-magnet 7 is placed in a gap, and the number of sub-magnets 7 is the same as the number of main magnets 6.

FIG. 9 explains how the current of the coil 2 shown in FIG. 7 is switched. In this linear motor, each coil 2
The Hall elements 3 arranged in each coil 2 and main magnet 6
When the magnets face each other, the polarity of the sub magnet 7, which has the same polarity as the main magnet 6, is detected, and the coil 2 is moved so that thrust is generated in the coil 2.
Determine the direction of energization. Figure 9 (a) and (b)
indicates the position of the mover at which the current of the first coil should be switched. The Hall element 3 detects the magnetic field O of the sub-magnet 7 at this position.

(c) to (e) in Figure 9 show the positions of the mover that switches the current in the second coil, and (f) to (i) in the same figure show the positions of the mover that switches the current in the third coil. show.

In the example of the linear motor shown in FIGS. 7 to 9, the number of coils 2 facing the movable yoke 5 is as large as three. In addition, the number of coil pieces 4 facing the main magnet 6 is six, but
Of these, four always contribute to thrust. The total width of the coils contributing to this thrust is 4c. The number of sub-magnets 7 for magnetic pole detection is the same as the number of main magnets, and the length of mover yoke 5 is 4 (number of sub-magnets 7) x 3c (width of sub-magnet 7) = 12c.
That's all.

4 to 6 show explanatory diagrams of a conventionally known 90-degree energizing type linear motor.

In the conceptual diagram of the linear motor shown in Fig. 4, 1 is a stator yoke, 2 is a coil, 3 is a Hall element for magnetic pole detection, 4 is a coil piece of the coil 2 that contributes to the thrust, 5 is a movable yoke, and 6 is a The main magnet 7 is a sub magnet for magnetic pole detection. Further, d indicates the width of the coil piece 4 that contributes to thrust among the coils 2 placed on the stator yoke 1. When securing the same stroke width of the mover as the linear motor shown in Fig. 7, d
=1.5c. The total width of the coil 2 is 3d, and the first
and the second coil are placed with a gap between them.The second and third coils are placed with a gap 2d apart.The third and fourth coils are placed without a gap.Hall element for magnetic pole detection 3
is placed in the center of each coil.

The width of the main magnets 6 placed on the mover yoke 5 is d, and the interval between each main magnet 6 is also d. The width of the sub-magnets 7 for magnetic pole detection is 2d, each sub-magnet 7 is placed without any gap, and the number of sub-magnets 7 is equal to the number of main magnets 6+1.

FIG. 6 explains how the current in the coil of the linear motor shown in FIGS. 4 and 5 is switched. In this linear motor, when each coil 2 and the main magnet 6 face each other, the magnetic pole detection Hall element 3 arranged for each coil 2 detects the polarity of the sub magnet 7 having the same polarity as the main magnet 6, and The direction of energization of the coil 2 is determined so that thrust is generated in the coil 2. (a) and (b) of FIG. 6 show the position of the movable element at which the current of the first coil should be switched. At this position, the magnetic pole detection Hall element 3 is connected to the magnetic pole detection sub-magnet 7.
Detects the magnetic field O.

(C) to (e) in FIG. 6 show the positions of the mover that switches the current of the second coil, and (f) to (h) show the positions of the mover that switches the current of the third coil.

In the examples of the linear motors shown in FIGS. 4 to 6, the number of coils 2 facing the movable element 5 is as small as two. The number of coil pieces 4 facing the main magnet 6 is four, but only two of them always contribute to the thrust, and the total width of the coil pieces contributing to the thrust is 2d=3c. The number of sub magnets 7 for magnetic pole detection is the number of main magnets + 1, and the length of mover yoke 5 is 5 (number of sub magnets 7) x 2d (width of sub magnet 7) = 10 d.
=15c or more.

Therefore, the movable yoke 5 is longer and heavier than the conventional example shown in FIG. 7. Furthermore, compared to the conventional example shown in FIG. 7, the thrust is reduced to 3/4, and the weight of the movable element is increased, so that the acceleration obtained by this linear motor is reduced. Compared to the linear motor shown in FIG. 7, the number of coils facing the mover is small (and the number of drive circuits that energize the coils is also small).

[Problems to be Solved by the Invention] As described above, in the 120-degree energizing type linear motor, the number of coils facing the main magnet is three, which increases the number of drive circuits that energize the coils.

Further, in a conventional 90-degree current-carrying type linear motor, the number of coil pieces contributing to thrust among the coils facing the main magnet is always two, and the thrust is small. In addition, since five sub-magnets are required for magnetic pole detection, the length of the mover is long.
The weight of the mover also increases. Moreover, the thrust force obtained by this linear motor is small (and the acceleration obtained by this linear motor is small because the movable element is heavy).

Therefore, the first object of the present invention is to provide a movable magnet type DC brushless linear motor that has a larger maximum thrust than the conventional 90-degree energizing type linear motor (and can obtain greater acceleration by reducing the weight of the mover). Our goal is to provide the following.

A second object of the present invention is to reduce the number of coils facing the main magnet compared to the conventional 120-degree current-carrying linear motor.
An object of the present invention is to provide a movable magnet type direct current brushless linear motor that can reduce the number of drive circuits that energize the coils.

[Means for Solving the Problems 1] The present invention provides a 90-degree energizing type linear motor, which is equipped with a coil and a Hall element for detecting magnetic poles on the stator side, and a main magnet for driving and a sub-magnet for detecting magnetic poles on the movable element side. The motor is characterized in that the width of the main driving magnet is set to twice the width of the coil piece.

Here, when the width of the coil piece contributing to the thrust is d,
The first and second magnetic pole detection Hall elements are placed 0.7d to the right from the center of the corresponding coil, and the third and fourth magnetic pole detection Hall elements are placed at the center of the corresponding coil. Then, the width of the first sub-magnet among the sub-magnets for magnetic pole detection is set to 1.
5d, the width of the second sub-magnet is 2.1 d, the width of the third sub-magnet is 2.1 d, the width of the fourth sub-magnet is 2.3 d, and the signal of each Hall element is converted into a signal processing logic. It is preferable that the width of the four sub-magnets be made the same as the width of the four main magnets by processing with the apparatus.

[Function] According to the present invention, the linear motor is energized at 90 degrees,
The width of the main magnet is twice the width of the coil piece.

This makes it possible to obtain up to twice the thrust of a conventional 90-degree energized linear motor. Also,
The maximum value of the coil width contributing to thrust is 4d=6c,
It is thicker than the conventional 120 degree current-carrying type linear motor.

Furthermore, in the present invention, the number of sub magnets is the same as the number of main magnets, and the total width of each sub magnet is the same as the total width of each main magnet. As a result, the width of the mover can be made shorter than that of conventional 90-degree energizing type linear motors, and the weight of the mover is also lighter.The width of the mover is 8d = 12c,
It is almost the same as a conventional 120 degree current-carrying linear motor.

In the linear motor according to the present invention, each Hall element is arranged and the width of each sub-magnet is determined so that changes in the magnetic pole of the main magnet with respect to the coil can be correctly detected with the same number of sub-magnets as the main magnets facing the Hall element. ing. The signals detected by each Hall element are sent to a logic operation element placed on the stator, and the logic operation element performs a logical operation on these signals to generate a signal for switching the current in each coil.

As described above, the linear motor according to the present invention has a larger thrust (and the weight of the mover is lighter) than the conventional 90-degree current-carrying type linear motor, so it can obtain a large acceleration. The number of coils is also smaller than that of conventional 120-degree energizing linear motors, and the number of drive circuits that energize the coils can be reduced.

[Embodiment 1] Hereinafter, an embodiment of the linear motor according to the present invention will be described in detail with reference to FIGS. 1 to 3.

FIG. 1 is a plan view showing the principle of an embodiment of the present invention, FIG. 2 is a front view showing the linear motor of this embodiment, and FIG. 3 is a diagram showing the procedure for switching the coil current.

As shown in FIG. 1, in this embodiment, a coil 2. Hall element for magnetic pole detection 3. Logical operation device 8.
Wiring 9 is arranged.

Among the coils 4, the width of the coil piece 4 that contributes to the thrust is d. The first coil and the second coil are placed in a gap,
The second and third coils are arranged at an interval of 2d, and the coils are arranged in this manner repeatedly thereafter.

Regarding the magnetic pole detection Hall element 3, the first Hall element is placed at a position approximately 0.7 d from the center of the first coil. Second. Third. The fourth Hall element is placed at the left end of the corresponding coil. Each Hall element 3 is connected to a logical operation device 8 through an electric wire 9.

A main magnet 6 and a sub-magnet 7 for magnetic pole detection are arranged on the movable element yoke 5. The width of the main magnets 6 is 2d, and they are placed without any gaps.

The number of sub magnets 7 is equal to the number of main magnets 6, the width of the first sub magnet is approximately 1.5 d, the width of the second and third sub magnets is approximately 2.1 d, and the width of the fourth sub magnet is approximately 2.3 d, and each is placed without any gaps. The sum of the widths of each main magnet and the sum of the widths of each sub-magnet are equal to 1
0d = 15c.

In the linear motor according to this embodiment, each pole element 3 is arranged so that a change in the magnetic pole of the main magnet 2 with respect to the coil 1 can be correctly detected by the sub-magnet 7 facing the magnetic pole detection Hall element 3. The width of each sub-magnet is determined by

The signals detected by each Hall element 3 are sent to a logic operation device 8 placed on the stator, and the logic operation device 8 performs a logic operation on these signals to generate a signal for switching the current of each coil 2.

Next, with reference to FIG. 3, a control example will be described in which the magnetic pole signal detected by the pole element 3 is logically operated by the logical operation processing unit 8 to switch the current of each coil.

(a) to (b) of FIG. 3 show the position of the movable element at which the current of the first coil should be switched. In (a), the magnetic field O of the sub-magnet is detected by the first Hall element. (b)
Then, the magnetic field O of the sub magnet is detected by the fourth pole element,
The logic operation device 8 switches the current of the first coil.

(C) to (f) in FIG. 3 show the position of the movable element that switches the current of the second coil. In (C) and (d), the second and third Hall elements 3 respectively detect the magnetic field O of the sub-magnet 7, and the logic operation device 8 switches the current in the coil 2. (e) turns off the current in the second coil
However, each Hall element cannot detect the magnetic field O of the sub-magnet only at this position, and the position of the mover becomes (f
), the current in the third coil is turned off.

(g) to (j) in FIG. 3 show the positions of the mover at which the current of the third coil should be switched. At each position, a third Hall element detects the magnetic field O of the sub-magnet and switches the current in the third coil.

The above-mentioned linear motor has a larger thrust than the conventional 90-degree energizing type linear motor, and the mover is also lighter.
I was able to obtain a large amount of acceleration.

Additionally, the number of coils facing the main magnet is smaller than in conventional 120-degree energizing type linear motors (and the number of drive circuits that energize the coils can be reduced).

[Effect of the invention 1] According to the linear motor of the present invention, a larger acceleration can be obtained than the conventional 90-degree energized linear motor, and when used for driving knitting needles of a flat knitting machine, for example, it can support higher-speed knitting operations. becomes possible.

Further, in the linear motor according to the present invention, the number of drive circuits for coil energization can be reduced compared to the conventional 120-degree energizing type linear motor, and the device can be made more compact.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the principle of an embodiment of the present invention, FIG. 2 is a front view showing the linear motor of this embodiment, and FIG. 3 is a diagram showing the procedure for switching the coil current of this embodiment. Fig. 4 is a plan view showing the principle of a 90-degree conduction type linear motor according to the prior art, Fig. 5 is a front view of the linear motor shown in Fig. 4, and Fig. 6 shows the current of the coil shown in Fig. 4. Figure 7 is a plan view showing the principle of a conventional 120-degree energizing type linear motor, Figure 8 is a front view of the linear motor shown in Figure 7, Figure 9 is shown in Figure 7. FIG. 3 is a diagram showing the principle of switching the current of the coil. DESCRIPTION OF SYMBOLS 1... Stator yoke, 2... Coil, 3... Hall element for magnetic pole detection, 4... Coil piece contributing to thrust, 5... Mover yoke, 6... Main magnet, 7... Sub-magnet for magnetic pole detection, 8... Logical operation device, 9... Wiring.

Claims (1)

[Claims] 1) A coil and a Hall element for magnetic pole detection are provided on the stator side,
9 with a main magnet for driving and a sub magnet for magnetic pole detection on the mover side
A movable magnet DC brushless linear motor of 0-degree energization type, characterized in that the width of the main driving magnet is set to twice the width of the coil piece. 2) When the width of the coil piece contributing to the thrust is d, the first
and the position of the second magnetic pole detection Hall element is placed 0.7d to the right from the center of the corresponding coil, and the position of the third and fourth magnetic pole detection Hall elements is placed at the center of the corresponding coil, The width of the first sub-magnet among the sub-magnets for magnetic pole detection is 1.5d.
, the width of the second sub-magnet is 2.1d, and the width of the third sub-magnet is 2.
．． 1d, and the width of the fourth sub-magnet is 2.3d, and by processing the signals of each Hall element with a signal processing logic device, the width of the four sub-magnets is the same as the width of the four main magnets. The movable magnet type direct current brushless linear motor according to claim 1, characterized in that: