JP3219133B2 - Linear DC brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear DC brushless motor used, for example, for transporting articles, and more particularly to moving a movable element while detecting a position and stopping the movable element at a specified position. Linear DC
It relates to a brushless motor.

[0002]

2. Description of the Related Art The principle of operation of a movable magnet type three-phase linear motor will be described with reference to FIG. The stator 120 of the linear motor includes a plurality of coils 122A, 122B, 122
Are arranged in the longitudinal direction of the linear motor. Further, the mover 110 is configured by arranging a plurality of permanent magnets 112 such that the polarity is alternated along the longitudinal direction. Hall elements 130C, 130A, and 130B for detecting the polarity of the permanent magnet are provided on the stator 120 side.

[0003] Hall elements 130C, 130A, 130B
Detects a relative position between the coil and the permanent magnet to continuously generate a thrust between the coil and the permanent magnet, and switches an energizing direction of the coil. For example, the mover 110 at the position shown in (a) in FIG. 5 generates a thrust in the right direction in the figure between the coils 122A, 122B, and 122C that are energized in a certain direction and travels to the right. And Then, when the movable element 110 reaches the position shown in (b) in the drawing and the movable element 110 can no longer generate a thrust, the Hall element 130B outputs that the polarity of the magnet 12 has been switched from S to N, and the energizing direction of the coil 122B. And continuously generate thrust to the right. That is, the Hall element is placed so as to detect a thrust equilibrium position of the mover at which a thrust cannot be generated unless the direction of energization of the coil is switched.
Since there are three thrust equilibrium positions along the width of the permanent magnet 112, the Hall elements 130C, 130A, 130B
Can detect 1/3 of the width of the permanent magnet 112. For example, if the width of the permanent magnet is 24 mm, the Hall element is 8
The position of the mover 110 can be detected at a pitch of mm.

On the other hand, when the linear motor is used for transporting articles, it is necessary to stop the mover at a target position. Here, the linear motor used for the transfer is provided with a position detecting device having a high resolution, such as an encoder. That is, the detection of the position of the mover during traveling can be performed by counting the output of the Hall element.
Since the output of the Hall element has a low resolution and cannot accurately detect a target stop position, an encoder is mounted only for the purpose of detecting the stop position.

[0005]

The present inventor has attempted to develop a linear motor that can achieve high stopping accuracy without using an extremely expensive encoder. As this method, the idea of stopping the mover at a position where the thrusts of the coil and the magnet are balanced (step-out position) was obtained. That is, since the thrust is balanced at the position shown by the dotted line in FIG. 5, it has been devised to actively stop the mover at this position.

[0006] In realizing this method, a new problem has arisen. This problem will be described with reference to FIG. In the figure, the output waveforms of the Hall elements 130A, 130B, and 130C shown in FIG. 5 are shown as the A phase, the B phase, and the C phase. Then, similarly to the dotted line shown in FIG.
The dotted line shows the position where the thrust of the coil and the magnet can be balanced. As described above, the Hall element is arranged to reverse the output at a position where the thrust balances. For this reason, for example, when an attempt is made to stop at the position indicated by the dotted line indicated by (b) in the drawing, this position is just the phase A (the Hall element 13).
Since the output of 0A) is a position where it switches from 1 (high) to 0 (low), even if this position (b) is detected, it is not determined whether the output of the A phase is 0 or 1. Therefore, it is necessary to perform position detection only with the output of the B phase and the output of the C phase. In the output of the B and C phases, the output is constant within a range of 16 mm (B phase = 0, C phase = 0). In other words, the B-phase and C-phase outputs do not reverse unless the mover moves to the left of position (a) or to the right of position (c). That is, even if the position (b) is to be detected, a problem is expected that the stop operation cannot be performed properly because the position has a reduced resolution.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to stably stop a mover at a desired position without providing a position detecting device. It is to provide a linear DC brushless motor that can be used.

[0008]

In order to solve the above problems, the present invention provides a method of arranging a plurality of coils along a longitudinal direction.
Alternatively, a stator having a plurality of permanent magnets arranged alternately in polarity along the longitudinal direction and a plurality of permanent magnets arranged alternately in polarity along the longitudinal direction, or a plurality of coils. Movers arranged along the longitudinal direction;
For detecting the relative position of the permanent magnet and the coil
A first magnetic pole sensor composed of a plurality of magnetic pole detection elements arranged at a predetermined pitch; and a position detection signal of the first magnetic pole sensor.
More switching the energizing direction of the coil, along with moving the movable element, said movable by a signal of the first magnetic pole sensor
A linear DC brushless motor comprising a control means for positioning control the mover by detecting the position of the child, the front
At the same arrangement pitch as the magnetic pole detection element of the first magnetic pole sensor
Second magnetic pole sensor comprising a plurality of magnetic pole detection elements arranged
Is the magnetic pole detection element arrangement pitch with respect to the first magnetic pole sensor.
The control means detects the position of the mover from the first magnetic pole sensor and the second magnetic pole sensor, and stops the mover at a position where thrust can be balanced. This is a technical feature.

In the present invention, since the mover is stopped at the position where the thrust can be balanced, the stop can be stably stopped by generating a stop torque. The thrust equilibrium position refers to a position where the thrusts of a plurality of permanent magnets cancel each other when the coil is excited in a certain direction and the thrusts are balanced.
Here, since the detection signal of the first magnetic pole sensor is switched at the thrust equilibrium possible position, the detection accuracy (resolution) is reduced only by the detection signal of the first magnetic pole sensor. By using the output of the second magnetic pole sensor which is arranged to be displaced by ピ ッ チpitch from the magnetic pole sensor, the position is detected with high accuracy, so that a stable stopping operation can be realized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a linear DC brushless motor according to the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a movable magnet type linear motor for conveying articles according to a first embodiment of the present invention. The stator side of the magnet movable linear motor has a guide rail 40 formed by extrusion molding of aluminum or an aluminum alloy, a coil assembly 20 attached to a fixed portion 40a formed at the upper end of the guide rail 40, and a coil assembly 20. And a detachable cover 50 for covering. This guide rail 4
A rail portion 40b having a U-shaped cross section for running the running roller 16 is formed at the lower end side of 0.

On the other hand, the mover 10 includes a magnet 12 facing a stator coil 22 built in a coil assembly 20 and a mover frame 14 holding the magnet 12 therebetween.
A cart 18 for fixing the mover frame 14 and a cart 1
A carriage hanger 19 integrally formed with the carriage 8 and a traveling roller 16 supported in a direction perpendicular to the carriage 18. Note that a plurality of magnets 12 are arranged so that the polarities alternate in the vertical direction in the figure. Hall elements 30C, 30A, 30B for detecting the polarity of the magnet 12
(Only the Hall element 30C is shown in the figure) is attached to the coil assembly 20 side. Note that an auxiliary hall element is provided on the back side (back side of the paper surface) of the hall element 30C, similarly to the hall element.

The coil assembly (stator) 20 includes
The six stator coils 22 arranged horizontally are resin-sealed. Although not shown, such a coil assembly 20
Is the guide rail 40 of the linear DC brushless motor.
Are arranged along the line to form a stator.

Referring to FIG. 2, the configuration of the control circuit of the linear DC brushless motor according to this embodiment will be described. The linear DC brushless motor includes Hall elements 30A, 30B, 30 for detecting the polarity of the magnet 12 of the mover 10.
C and auxiliary Hall elements 32A, 32B, 32C are provided, and the microcomputer 62 detects the position of the mover 10 and excites the coil assembly 20 via the driver circuit 60 by the output of these Hall elements. The coil assembly 20 includes stator coils 22A and 22A.
D, stator coils 22B, 22E, stator coil 22
C and 22F are star-connected. The driver circuit 60
By opening and closing the switches 60A and 60B, the energization / excitation directions of the stator coils 22A to 22F are sequentially switched as the mover 10 moves.

Although only one set of coil assemblies 20 is shown in the figure for convenience of illustration, a plurality of coil assemblies 20 are arranged along the guide rail 40 as described above with reference to FIG. Please note that. Further, the Hall elements 30A, 30B, 30C and the auxiliary Hall elements 32A, 32B, 32C are provided for each coil assembly 20.

Next, the positional relationship among the coil assembly 20, the mover 10, the Hall elements 30A, 30B, 30C and the auxiliary Hall elements 32A, 32B, 32C will be described with reference to FIG. Note that, for convenience of illustration, the coils of the coil assembly 20 are stator coils 2
Note that only 2A, 22B, and 22C are shown, and only a part of the magnet of the mover 10 is shown.

On the coil assembly 20 side, a Hall element 3 for detecting the polarity of the magnet 12 of the mover 10 is provided.
0C, 30A and 30B are provided. Hall element 3
0C, 30A, 30B are coils 22A, 22B, 22
In order to continuously generate a thrust between the C and the coils 22D, 22E, and 22F (see FIG. 2) and the magnet 12, the relative positions of the two are detected and the energizing direction of the coil is switched. . That is, the Hall element detects a step-out position where the thrusts of the plurality of magnets 12 are balanced on the mover side unless the energizing direction of the coil is switched, and the thrust for moving the mover cannot be generated. It has been placed. In the drawing, the position where the output by the Hall element changes, that is, the detection position of the mover by the Hall element is indicated by a dotted line.

As shown in the figure, there are three out-of-step positions indicated by dotted lines where no thrust can be generated for each magnet 12, so that the Hall elements 30C, 30A and 30B
1/3 of the width of 2 can be detected. In this embodiment, the magnet 1
Since the width of 2 is 24 mm, the Hall element can detect at a pitch of 8 mm.

On the other hand, auxiliary Hall elements 32C, 32A,
32B is disposed at a detection position deviated by 4 mm from the detection positions of the Hall elements 30C, 30A, and 30B. That is,
The auxiliary hall element is arranged so as to be able to detect the magnets 12 at a pitch of 8 mm similarly to the hall element. The output is switched at a position indicated by a dashed line in the figure, which is shifted by 4 mm from a position indicated by a dotted line in the figure, at which the output is switched.

Here, the Hall elements 30C, 30A, 3
0B and waveforms of the outputs of the auxiliary hall elements 32A, 32B, and 32C with reference to FIG.
The operation of the C brushless motor will be described. In the figure,
The output of the Hall element 30A is referred to as A phase, the waveform of the Hall element 30B is referred to as B phase, and the waveform of the Hall element 30C is referred to as C phase. The auxiliary hall element 32
The outputs of A, 32B, and 32C are repeatedly high and low in the same manner as in the above-described Hall element.
The output synthesized by the logic circuit is represented as the output of the auxiliary sensor because the logic circuit (not shown) in the microcomputer 62 shown in FIG. here,
The logic circuit includes auxiliary Hall elements 32A, 32B, 32
Two out of C output high when high (1) and output low when two low (0).

The microcomputer 62 grasps the current position by counting the rise and fall of the outputs of the Hall elements 30C, 30A and 30B while traveling on the mover. That is, the output of the Hall element changes at the position indicated by the dotted line in the figure (rise / fall)
Therefore, for example, when the mover is sent to the right side in the figure, the count value is incremented at the timing when the output changes, and when the mover is sent to the left side, it is movable by decrementing the count value. Know the position of the child. That is, the microcomputer 62 controls the position of the mover while performing feedback control based on the signal from the Hall element.

On the other hand, when the microcomputer 62 stops the mover, in the present embodiment, the mover is moved at a point where the thrust of the mover can be balanced, that is, at a position shown by a dotted line in FIG. Stop. For example, when moving the mover from left to right in the figure and stopping it at the position (e), after passing through the position (d) (inverting the output of the phase B from 0 to 1), When the output of the auxiliary sensor is inverted (from 1 to 0), the coil is energized so as to lock the mover. That is, in order to stop at the position (e), switching to lock energization is performed in the following output state. A phase: No problem (that is, it may be 0 or 1) B phase: 1 C phase: 0 Auxiliary sensor: 0

At the time of the energization of the lock, the A phase (the mover coils 22A and 22D) and the B phase (the mover coils 22B and 22D)
2E), and no current in the C phase, so that the repulsive force between the plurality of magnets 12 of the mover at the position (e), that is, the rightward thrust and the leftward thrust are balanced. The movable element is stopped by generating the stopped torque.

As shown in FIG. 4, when the mover is stopped at the position (e), "open control" is performed to perform positioning within the minimum resolution of the Hall element. For this reason, it is necessary to switch to the lock energization as close as possible to the stop location for stable operation. Here, as described above with reference to FIG. 6, if the position is detected only by the output of the Hall element, the thrust equilibrium position corresponds to the position where one of the three Hall elements switches the output. The position is detected by the number of outputs, and the resolution is equivalently reduced. On the other hand, in the present embodiment, since the position is detected using the output of the auxiliary hall element together with the above-mentioned hall element, the lock energization can be started near the stop position.

In this embodiment, a system in which a fixed potential is applied to the stator coil, that is, a linear D type in which a voltage is applied to two of the three phases to generate thrust on the mover, is used.
Although the C brushless motor has been exemplified, the configuration of the present invention can also be applied to a linear DC brushless motor of a system in which three-phase voltages are applied simultaneously by adjusting the applied voltage.

Also, in the above embodiment, a magnet movable linear DC brushless motor having a coil disposed on the stator side and a magnet disposed on the mover side has been described as an example. The present invention can also be applied to a coil movable linear DC brushless motor in which a magnet is arranged and a coil is arranged on the mover side. Further, the configuration of the present invention can be applied not only to a three-phase linear DC brushless motor but also to a two-phase or four-phase or more linear DC brushless motor.

[0026]

As described above, according to the present invention, since the mover is stopped at the position where thrust can be balanced, a stop torque can be generated to stably stop the mover. Here, at the thrust equilibrium-possible position, the detection signal of the Hall element is switched, so that the detection accuracy (resolution) is reduced only by the detection signal of the Hall element, but it is deviated from the Hall element together with the Hall element. Since the position of the mover is detected with higher accuracy by using the output of the auxiliary hall element, a stable stop operation can be realized without using a dedicated position measuring device such as an encoder.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a mechanical configuration of a linear DC brushless motor according to an embodiment.

FIG. 2 is a block diagram illustrating a control circuit of the linear DC brushless motor according to the embodiment.

FIG. 3 is an explanatory diagram illustrating a positional relationship between a coil and a mover of the linear DC brushless motor according to the present embodiment.

FIG. 4 is a waveform chart showing output waveforms of the Hall element and the auxiliary Hall element shown in FIG. 3;

FIG. 5 is an explanatory diagram showing a positional relationship between a coil of a linear DC brushless motor and a mover.

FIG. 6 is a waveform chart showing an output waveform of the Hall element shown in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Mover 12 Magnet 20 Coil assembly (stator) 22A, 22B Stator coil 30A, 30B, 30C Hall element (first magnetic pole sensor) 32A, 32B, 32C Auxiliary hall element (second magnetic pole sensor) 40 Guide rail 60 Driver circuit 60A, 60B switch 62 Microcomputer (control means)

Claims (1)

(57) [Claims] 1. A stator comprising a plurality of coils arranged in the longitudinal direction or a plurality of permanent magnets arranged in the longitudinal direction so as to alternate in polarity, and a permanent magnet arranged in the longitudinal direction. A plurality of movers having a plurality of coils arranged alternately or a plurality of coils arranged in a longitudinal direction, and a mover for detecting a relative position between the permanent magnet and the coil.
A first magnetic pole sensor composed of a plurality of magnetic pole detection elements arranged at a predetermined pitch, and a direction of energization of the coil switched by a position detection signal of the first magnetic pole sensor to move the movable element ,
The position of the mover is detected by the signal of the first magnetic pole sensor.
And a control means for controlling the positioning of the mover by using the same arrangement pitch as the magnetic pole detecting element of the first magnetic pole sensor.
Magnetic pole sensor comprising a plurality of magnetic pole detection elements arranged in
The magnetic pole detecting element array picks up with respect to the first magnetic pole sensor.
And the control means detects the position of the mover from the first magnetic pole sensor and the second magnetic pole sensor, and stops the mover at a position where thrust can be balanced. A linear DC brushless motor.