JPH1056792A - Position detector for variable magnet linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detector for variable magnet linear motor in which any special reset operation is required after power interruption is recovered. SOLUTION: A current position calculating means calculates the current position of a moving piece 40 by counting up or down the detection signals of respective magnetosensitive elements 14a, 14b and 14c. When the current position of the moving piece 40 becomes indefinite due to power interruption or the like, a control means monitors the absolute position signal detected by an absolute position detecting means at the first operation of the moving piece 40 after power recovery. When the signal is varied, the current position value of the current position calculating means is reset to a corresponding absolute position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for a movable magnet type linear motor in which a movable element composed of a permanent magnet runs along a stator formed by connecting a plurality of coil units.

[0002]

2. Description of the Related Art At present, a movable magnet linear motor that excites a stator coil built in a stator to drive a movable element is used in a transfer line of a factory or the like. In this magnet movable type linear motor, a relative position between a mover permanent magnet and a stator coil is detected by a sensor provided on a stator side, and a stator coil attached to the stator is selectively excited. Drives the mover.

With reference to FIG. 6, the configuration of a movable magnet type linear motor according to the prior art will be described. The stator 110 is formed by connecting a plurality of coil units 112 each having the stator coil 17 therein. Along the stator coil 17 of the stator 110, the plurality of permanent magnets 4
4 is moved. The permanent magnet of the mover 40 and the stator coil 17 of each coil unit 112
Is detected by the sensor unit 14 provided in the coil unit 112. The sensor unit 14 includes three magneto-sensitive elements 14a, 14b, and 14c. Each of the magneto-sensitive elements 14a, 14b, and 14c is connected to a control unit 130 via a sensor bus line 32.

[0004] The control unit 130 is a transistor circuit based on a detection signal from the sensor unit 14.
6 to drive the stator coil 17 via the power bus line 38. That is, a detection signal from each of the magnetic sensing elements 14a, 14b, and 14c of the sensor unit 14 in the coil unit 112 in which the mover 40 is located is input to the OR circuit 22.
2 applies the output to the switch circuit 20. As a result, the switch circuit 20 connects the stator coil 17 where the mover 40 is located to the power bus line 38.

[0005]

In the conventional magnet movable linear motor according to the prior art, the current position of the mover is calculated by counting up and down the detection signal from the sensor unit. Then, the current position of the mover cannot be determined. For this reason, after returning from the power failure, the mover is moved to the home position, and at the home position,
After resetting the counter value of the current position, the calculation of the current position was restarted. Note that the current position value calculated by the backup power supply can be held even during a power failure, but if a power failure occurs while the mover is running, the movement amount due to the inertia of the mover after the power failure is detected. Since it was impossible, the current position could not be determined.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a position detecting device for a movable magnet type linear motor that does not require a special reset operation after a power failure recovery. Is to do.

[0007]

In order to achieve the above object, a position detecting apparatus for a movable magnet type linear motor according to the present invention comprises a fixed member formed by connecting a mover comprising a plurality of permanent magnets and a plurality of coil units. And a sensor disposed in each of the coil units for detecting a relative position between the mover permanent magnet and the stator coil, and energization switching means for switching energization to the stator coil based on a position detection signal from the sensor In the magnet movable linear motor consisting of: a current position calculation means for calculating the current position of the mover by counting up and down the detection signal of the sensor, and connected to the sensor via a selection switch, respectively,
An operation range of the mover is divided into a plurality of regions based on a detection signal of the sensor, an area where the mover is located, and an absolute position detection unit that detects an absolute position between each region, At the first operation of the mover, the absolute position signal of the absolute position detecting means is monitored, and when the signal changes, the current position value of the current position calculating means is reset to a corresponding absolute position value according to the change state. And a control means.

[0008]

The current position calculating means calculates the current position of the mover by counting up and down the detection signal of the sensor. When the current position of the mover becomes unknown due to a power failure or the like, the control means monitors the absolute position signal of the absolute position detection means at the first operation of the mover after recovery from the power failure. The current position value of the current position calculating means is reset to a corresponding absolute position value according to the state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
FIG. 2 is a circuit diagram of a movable magnet type linear motor according to the embodiment, and FIG. 2 is a perspective view of the linear motor. As shown in FIG. 2, the stator 10 is formed by connecting a plurality of coil units 12 each including a coil plate 16 and a substrate 17.

In the linear motor, a mover 40 runs on a single running track 18 formed by connecting a plurality of the coil plates 16. The coil plate 16 of the coil unit 12 has two sets of stator coils 16a, 16b, 16c and 16a ', 1
6b'16c 'are built in, and these are three-phase star connected in series as shown in FIG. The mover 40 composed of a plurality of permanent magnets 44 is connected to the current flowing through the stator coils 16 a to 16 c ′ of the coil plate 16 and the permanent magnet 4.
Thrust is given by interaction with the magnetic flux of No. 4.

The mover 40 is formed by arranging and fixing a plurality of permanent magnets 44 having the same shape on a yoke 42. The plurality of mover magnets 44 are magnetized in the thickness direction, and adjacent poles have different polarities as shown in FIG. An extension 46 is provided on one side surface of the yoke 42, and the extension 46 holds a plurality of detection magnets 48. The detection magnet 48 is magnetized so as to have the same polarity as that of the plurality of permanent magnets 44 located above the detection magnet 48. The sensor unit 14 for detecting the relative position between the permanent magnet 44 of the mover 40 and the stator coils 16a to 16c 'is mounted on the substrate 17 of the coil unit 10.
Is placed on top. The sensor unit 14 is provided at a position facing the detection magnet 48, and is provided at each coil unit 12, and is fixed to the mover permanent magnet 44 regardless of which coil unit 12 the mover 40 is located at. The position relative to the child coils 16a to 16c 'can be detected.

Referring to FIG. 1, which is a circuit diagram of the coil unit 12, an electric configuration of the linear motor according to the first embodiment will be described. Mover permanent magnet 44 and stator coil 1
The sensor unit 14 for detecting a relative position with respect to each of the stator coils 16a, 16a ',
b, 16b ', 16c, 16c' and three magneto-sensitive elements 14a, 14b, 14c.
4a, 14b and 14c are connected to a control circuit 34 of the control unit 30 via a sensor bus line 32. The sensor bus line 32 includes an a-phase signal line 32a connecting the magnetic sensing elements 14a of the respective sensor units 14 so that the detection angles match, and a b-phase signal line 32a connecting the magnetic sensing elements 14b so that the detection angles match. A signal line 32b;
Each magneto-sensitive element 14c is connected so that the detection angles coincide.
And a phase signal line 32c. The control circuit 34
Are connected to a transistor circuit 36 that connects a power supply and a power bus line 38. Then, the coil plate 16
Are connected to the power bus line 38 via the switch circuit 20. On the other hand, a detection signal from the sensor unit 14 is applied to the switch circuit 20 via an OR circuit 22.

Each magnetic sensing element 14 of the sensor unit 14
As a, 14b and 14c, for example, Hall elements are used. The distance between the magnetic sensing elements 14a, 14b, and 14c is set to 1/3 of the magnetic pole pitch of the mover permanent magnet 44.
A signal is output at a pitch of / 3.

Each magneto-sensitive element 14a of the sensor unit 14,
The detection signals from 14b and 14c are input to the OR circuit 22. The OR circuit 22 applies an output to the switch circuit 20 in response to an input of one of the magneto-sensitive elements. As a result, the switch circuit 20 switches the coil plate 16 to an energizable state by closing the two switches 20a and 20b because the coil plate 16 is a three-phase star connection.

The OR circuit 22 is further connected to an absolute position signal line 52 composed of two signal lines 52d and 52e via a selection switch 54. When the selection switch 54 is connected to the one contact 54d side, the output of the OR circuit 22, that is, the sensor unit 1
4 is applied to the signal line 52d. When the other contact 52e is connected, the output of the OR circuit 22 is sent to the signal line 52e.

As described above, the coil unit 12 is connected by a necessary length as the traveling path 18 of the mover. In this connection, the sensor bus line 32, the absolute position signal line 52, and the power bus line 38 are connected. The adjacent coil units 12 are connected to each other.

The control unit 30 includes a control circuit 3
4 and a transistor circuit 36, and a control circuit 34
Supplies a drive signal to the transistor circuit 36 based on the detection signal from the sensor unit 14. Transistor circuit 3
6, six transistors Tra, based on the drive signal,
Tra ', Trb, Trb' and Trc, Trc '
Are turned on and off, and each stator coil 16 of the coil plate 16 is turned on.
a to 16c ′ are excited. The excitation phases of the stator coils 16a to 16c 'of the coil plate 16 are
4 and the stator coils 16 a to 16 c ′ and the operating direction of the mover 40.

Next, the operation of the linear motor according to the above configuration will be described. When the target position is determined, the mover 4
The sensor unit 14 provided in the coil unit 12 where the position 0 is located includes the mover permanent magnet 44 and the stator coil 16a.
-16c 'is detected. The detection signal is sent to the control circuit 34 via the sensor bus line 32 and also to the switch circuit 20 via the OR circuit 22. As a result, the switch circuit 20 closes the two switches 20a and 20b to switch the power bus line 38 to a state where power can be supplied to the stator coils 16a to 16c '. On the other hand, based on the detection signal sent to the control circuit 34 via the sensor bus line 32 and the operation direction of the mover 40, the control circuit 34 sequentially determines the excitation phase and determines the transistors Tra and Tra 'of the transistor circuit 36. , Trb,
Trb ', Trc, and Trc' are turned on and off. As a result, the stator coils 16a to 16c 'are excited, a thrust is generated in the mover 40 based on the Fleming left hand rule, and the mover 40 moves toward the target position.

When the mover 40 sequentially corresponds to the adjacent coil unit 12 as the mover 40 moves, the sensor unit 14 provided in the adjacent coil unit 12
The detection signal is transmitted to the control circuit 34 and the switch circuit 20.
To send to. As a result, the switch circuit 20 of the adjacent coil unit 12 enables the power supply from the power bus line 38 to the stator coils 16 a to 16 c ′ of the coil unit 12. Hereinafter, similarly, the mover 40
Thrust is continuously applied to In addition, the coil unit 1
When the mover 40 passes through the sensor unit 14 provided in the sensor unit 2, the sensor unit 14 stops outputting a detection signal, and the coil unit 12 turns on the switch circuit 20 to energize the stator coils 16a to 16c '. Becomes impossible.

Here, the position detection of the mover 40 will be described with reference to FIG. FIG. 4 shows the control circuit 3 shown in FIG.
4 and the relationship between the coil unit 12 and the sensor unit 14 are schematically shown.
14b and 14c, ie, a,
The signal waveforms of the b and c phase signal lines 32a, 32b and 32c and the absolute position signal lines 52d and 52e are shown. Here, as a coil unit, 12-1
Only the six coil units No. to 12-6 are shown for convenience of illustration.

When the mover 40 travels rightward in the figure from the coil units 12-1 to 12-2, the magneto-sensitive element 1
The detection signals are output in the order of 4c, 14b, and 14a. The control circuit 34 calculates the current position of the mover 40 by counting up the number of rises and falls of the signal waveform. On the other hand, when traveling from the coil unit 12-2 to the left side in the figure from the coil unit 12-2, detection signals are output in the order of the magneto-sensitive elements 14a, 14b, and 14c.
Thus, the traveling direction of the mover 40 is known, and the current position of the mover 40 is continuously calculated by counting down the number of rises and falls of the signal waveform.

Here, the coil units 12-1 and 12
The -2 selection switch 54 is connected to one contact 54d. Also, the coil units 12-5 and 12-
The sixth selection switch 54 is connected to the other contact 52e. The selection switches 54 of the coil units 12-3 and 12-4 are not connected to any of the contacts.

That is, the mover 40 is connected to the coil unit 12-
1, 12-2, the magnetic sensing elements 14a, 14b, 14c are connected to one absolute position signal line 52d.
, A high-level detection signal is output through the OR circuit 22, and the other absolute position signal line 52e is maintained at a low level. Here, when the mover 40 is at the left end position (start end) of the coil unit 12-1 in the drawing, it is P0, when it is at the right end position of the coil unit 12-2, it is P1, and one absolute position signal line 52d is [High level], the area where the other absolute position signal line 52e is [low level] is defined as an X area.

The mover 40 is a coil unit 12-
When they correspond to 3, 12-4, the absolute position signal lines 52d and 52e are both kept at the low level.
Here, when the mover 40 is at the right end position of the coil unit 12-4 in the figure, it is defined as P2.
The area where the absolute position signal lines 52d and 52e up to [low level] are both Y areas.

The mover 40 is mounted on the coil unit 12-.
5 and 12-6, one absolute position signal line 52d is kept at a low level, and the other absolute position signal line 52e outputs a high level detection signal from the OR circuit 22. Here, when the mover 40 is at the right end position (end) of the coil unit 12-6 in the figure, P
Let E be an area in which one of the absolute position signal lines 52d from the position P2 to the position PE is [low level] and the other absolute position signal line 52e is [high level].

In this embodiment, the mover 40
The absolute position signal line 5
From the signal levels of 2d and 52e, the mover 40 is set to X, Y, Z
It is possible to recognize which of the areas belongs.
For example, when one absolute position signal line 52d is at [high level] and the other absolute position signal line 52e is at [low level], it is in the X area, and when both are at [low level], it is in the Y area. Line 52
d is [low level] and the other absolute position signal line 52e
Is [high level], it can be seen that it belongs to the Z region. Further, the absolute positions of two points P1 and P2 can be detected.

In the teaching operation at the time of the initial setting, the control circuit 34 previously stores P0, P1, P2, and PE shown in FIG.
And the absolute position value of PX described later is stored in a non-volatile memory, and when the current position value of the mover 40 is lost due to a power failure, when passing through the absolute positions P0, P1, P2, and PE,
Reset to the position value held in the non-volatile memory.

The reset operation after the recovery from the power failure by the control circuit 34 will be described in more detail with reference to FIG. In the first operation of the mover 40 after the recovery from the power failure, it is first detected in which of the X, Y, and Z regions the mover 40 is located. Then, the area where the mover 40 is located is compared with the target position. If the mover 40 is located on the left side of the target position, and if the target position is located within the area where the mover 40 is located, X from the absolute position P0 The value of the absolute position PX deviated to the left by more than the stroke of the area is set as a temporary current position value of the mover 40. When the mover 40 is located on the right side of the target position, the value of the absolute position PE is set as a temporary current position value of the mover 40.

In this state, when the mover 40 is operated toward the target position, during this operation, the control circuit 34 monitors a change in the signal level of the absolute position signal lines 52d and 52e. At this time, the current position value of the mover 40 is reset to one of the absolute positions P1 and P2 held in the memory according to the state of the change.
Thereafter, the operation of the mover 40 is continued. On the other hand, if the mover 40 cannot operate before the signal levels of the absolute position signal lines 52d and 52e change, the mover 40
Is determined to be at the beginning or end, the current position value of the mover 40 is reset to the value of the absolute position P0 or PE stored in the memory according to the operation direction, and the operation of the mover 40 is performed in the same manner as described above. continue. Thereby, the mover 40 can accurately reach the target position. As described above, when the mover 40 is located on the left side of the target position and when the target position is within a certain area of the mover 40, the value of the absolute position PX is set as the temporary current position value of the mover 40. When both the mover 40 and the target position are in the X region, and the value of the absolute position P0 is set as the temporary current position of the mover 40, the mover 40 reaches the target position in the X region. This is because a stop may occur and the current position value of the mover 40 may not be reset by the first operation of the mover 40 after the recovery from the power failure.

Here, in the conventional magnet movable linear motor, when the current position of the mover is lost due to a power failure, the mover is moved to the origin position and the counter value of the current position is reset at the origin position. Needed.
On the other hand, in the present embodiment, as described above, to which region of the X, Y, and Z the mover 40 belongs, and the absolute positions P1 and P2 of two points between the regions are indicated by the absolute position signal line. Since it can be detected by the signals from 52d and 52e, the running direction of the mover 40 is determined at the time of the first operation of the mover 40 without performing a special reset operation even after recovery from the power failure. Absolute positions P0, P1, P
2. When the mover 40 passes through PE, the current position value can be automatically reset.

In the above-described embodiment, a three-phase excitation type movable magnet type linear motor using three magnetic sensing elements 14a, 14b, 14c has been described as an example. The present invention is also applicable to a two-phase excitation type movable magnet linear motor using an element. Furthermore, in the embodiment described above, 2
Three types of regions are set by applying 2-bit position information using the absolute position signal lines 52d and 52e. For example, three absolute position signal lines are provided, and 3-bit position information is set. It is also possible to set eight types of regions by applying.

[0032]

As described above, according to the position detecting apparatus for a movable magnet type linear motor of the present invention, at the time of the first operation of the mover after the restoration from the power failure, the area to which the mover belongs can be detected and the traveling can be started. At the same time, since the reset operation can be automatically performed during traveling, a special reset operation after the recovery from the power failure is not required.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a movable magnet linear motor according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a movable magnet linear motor according to the embodiment.

FIG. 3 is a circuit diagram of a stator coil of the movable magnet linear motor shown in FIG. 1;

FIG. 4 is a connection diagram of the movable magnet linear motor shown in FIG. 1;
And a signal waveform diagram of a sensor.

FIG. 5 is a circuit diagram showing a configuration of a movable magnet type linear motor according to the related art.

[Explanation of symbols]

 Reference Signs List 10 Magnet movable linear motor 12 Coil unit 14a, 14b, 14c Magnetic sensing element 16 Coil plate 20 Switch circuit 22 OR circuit 32a A-phase signal line 32b B-phase signal line 32c C-phase signal line 34 Control circuit 52d Absolute position signal line 52e Absolute position signal line

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[Procedure amendment]

[Submission date] November 11, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

Claims (1)

[Claims] 1. A mover including a plurality of permanent magnets, a stator formed by connecting a plurality of coil units, and a relative position between the mover permanent magnet and a stator coil disposed in each of the coil units. And a power supply switching means for switching the power supply to the stator coil based on a position detection signal from the sensor. A current position calculating means for calculating a current position of the child; a sensor connected to each of the sensors via a selection switch; dividing an operation range of the movable member into a plurality of regions based on a detection signal of the sensor; Position detecting means for detecting an area having an area and an absolute position between the areas; and detecting the absolute position at the time of the first operation of the mover after recovery from power failure. Control means for monitoring the absolute position signal of the means, and resetting the current position value of the current position calculating means to a corresponding absolute position value according to the change state when the signal changes. Position detection device for movable magnet type linear motor.