JP2950148B2 - Linear 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 motor for driving a mover by exciting a stator coil built in a stator.

[0002]

2. Description of the Related Art At present, a linear motor that excites a stator coil built in a stator to drive a mover is used for opening / closing an automatic door requiring linear force, or for a transfer line of a factory. Have been. In this linear motor, the position of the mover is detected by a position sensor provided on the stator side, and the mover is driven by selectively exciting a stator coil attached to the stator. This linear motor is required to have a high speed when the overall length is long, for example, when the linear motor is used for an article conveying path.

The thrust T of the linear motor that determines the speed of the mover is a function of the number of turns N of the stator coil and the coil current I, and is expressed by T∝NI. The coil current I is obtained by subtracting the back electromotive force Vb induced in the stator coil from the voltage V applied to the stator coil, and dividing the result by the resistance R of the stator coil, that is, I = [V−Vb ] / R.
On the other hand, the back electromotive force Vb is a function of the speed v of the mover and the coil inductance L of the stator coil, and is expressed by Vb∝vL. The speed v of the mover saturates as the speed v increases and the back electromotive force Vb increases, thereby being limited.

[0004]

For this reason, the applied voltage V
In order to increase the speed v of the mover while keeping the constant, it is necessary to reduce the coil inductance L by reducing the number of turns N of the stator coil and to suppress the back electromotive force Vb. However, when the number of turns N of the stator coil is reduced, when the mover is low speed and the back electromotive force Vb is small, the coil current I flowing through the stator coil is increased, so that not only the loss is increased but also the large current is increased. In order to maintain the insulation of the stator coil against the heat generated by the motor, it is necessary to increase the size of the stator, that is, the linear motor. On the other hand, in the method of increasing the applied voltage V to increase the speed of the mover, the stator coil current can be reduced by lowering the voltage when the mover is at a low speed, and current loss at a low speed can be suppressed. However, there is a problem that the cost increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a linear motor capable of driving a mover at a high speed and having a small loss when the mover is at a low speed.

[0006]

According to a first aspect of the present invention, there is provided a linear motor having a mover and a stator having a plurality of stator coils arranged therein. The stator 10 is provided with a small number of stator coils 16a to 16
It is characterized in that c ′ is arranged and stator coils 16 g to 16 i ′ having a large number of turns are arranged at a position where the speed of the mover 40 is low.

[0009]

According to the linear motor of the present invention having the above configuration,
In the first embodiment, since the stator coils 16g to 16i 'having a small number of turns, that is, having a small coil inductance, are arranged at a position where the mover 40 is to be moved at a high speed. The back electromotive force induced in the stator coil decreases, a relatively large coil current flows, and the thrust, which is a function of the coil current, increases, so that the mover 40 can move at high speed. On the other hand, mover 4
Since the number of windings, that is, the stator coils 16a to 16c 'having a large resistance value, is arranged at a position where 0 moves at a low speed, the stator coil at a low-speed moving position of the mover 40 having a small back electromotive force is arranged. Only relatively small coil currents flow through 16a-16c '. Therefore, it is possible to use a stator coil having a small heat capacity. In a preferred embodiment, the small number of turns of the stator coils 16g-1g
Since a thick coil wire, that is, a coil wire having a small resistance value is used for 6i ', the stator coil 1 having a small number of turns is used.
At 6 g to 16 i ′, that is, at a position where the mover 40 moves at a high speed, a large coil current flows and a large thrust can be generated. On the other hand, a stator coil 1 having a large number of turns
Since a thin coil wire, that is, a coil wire having a large resistance value is used for 6a to 16c ', the coil current is reduced at a position where the stator coil 16a to 16c' having a large number of turns, that is, the mover 40 is at a low speed. It is possible to limit. In still another preferred embodiment, stator coils 16d to 16f 'having an intermediate number of turns are arranged between stator coils 16g to 16i' having a small number of turns and stator coils 16a to 16c 'having a large number of turns. The mover 4
0 can be smoothly increased and decelerated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a linear motor according to an embodiment of the present invention, and FIG. 2 is a perspective view of the linear motor.
As shown in FIG. 2, the stator 10 is provided with a low-speed coil plate 16.
A and a low-speed coil unit 12A comprising a substrate 52;
A plurality of medium-speed coil units 12B each including a medium-speed coil plate 16B and a substrate 52 and a plurality of high-speed coil units 12C each including a high-speed coil plate 16C and a substrate 52 are connected. FIG. 2 shows a part of the starting side (left side stroke end) of the stator 10, and several low-speed coil units 12A (not shown) are further connected to the left side of the low-speed coil unit 12A shown in the figure. On the other hand, several hundred high-speed coil units 12A are further connected to the right side of the illustrated high-speed coil unit 12A in the figure, and several high-speed coil units 12A are further connected to the right side thereof, that is, near the end (right stroke end). The medium speed coil unit 12B and several low speed coil units 12A are connected.

The linear motor includes the coil plates 16A,
The mover 40 is driven on one traveling track 54 formed by connecting a plurality of 6B and 16C. The coil plate 16A of the low-speed coil unit 12A contains six stator coils 16a, 16b, 16c and 16a ', 16b', 16c ', each of which is wound relatively many times with a thin coil wire. The coil plate 16B of the medium-speed coil unit 12B has
Six stator coils 16d, 16e, 16f and 16d ', 16 wound in medium number with medium thickness coil wire
e'16f 'is built in. On the other hand, a coil plate 16C of the high-speed coil unit 12C has six stator coils 16g, 16
h, 16i and 16g ', 16h'16i' are built-in. As described above, the stator coils 16a to 16c 'of the low-speed coil unit 12A are wound with many thin coil wires, and the stator coils 16d to 16d of the medium-speed coil unit 12B.
Reference numeral 16f 'denotes a medium-sized coil wire wound in a medium number of turns, and the stator coil 1 of the high-speed coil unit 12C.
Since 6 g to 16 i ′ are wound with a few thick coil wires, the stator coils 16 a to 16 i ′ are formed to have substantially the same size, so that accommodation in the coil plate is facilitated. A mover 40 including a plurality of mover magnets 44
Is given a linear thrust by the magnetic force generated in the stator coils 16a to 16i 'of the coil plates 16A, 16B, 16C.

The mover 40 is formed by arranging and fixing a plurality of mover magnets 44 of 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 for detection by the sensor units 14 and 14 ′ described later.
The detection magnet 48 is magnetized so as to have the same magnetism as that of the plurality of mover magnets 44 located above the detection magnet 48. The detection magnet 48 of the mover 40, that is, the sensor unit 14 for detecting the magnetic force of the mover magnet 44, is provided with coil plates 16A, 16B, 16C.
Are arranged along. Sensor units 14, 14 '
Are provided at both ends of each of the coil units 12A, 12B, and 12C, and the mover 40 is
This can be detected at any position on B and 12C.

Referring to FIG. 1, which is a circuit diagram of the low-speed coil unit 14A, the electrical configuration of the linear motor according to the embodiment will be described. The sensor units 14 and 14 ′ for detecting the position of the mover 40 include three magnetic sensing elements 14.
a, 14b, 14c, each of the magneto-sensitive elements 14a, 14
b and 14c are connected via a sensor bus line 17 to a control unit 30 for controlling the mover 40. The control unit 30 is connected to the switch circuit 20 via the power bus line 18. The switch circuit 20 is connected to the lines 20a, 2a,
0b is connected to the coil plate 16A. On the other hand, detection signals from the sensor units 14 and 14 ′ are applied to the switch circuit 20 via an OR circuit 22.

As described above, the coil plate 16A has six stator coils 16a, 16b, 16c and stator coils 16a 'and 16a'
16b 'and 16c' are integrated by resin sealing, and are arranged along the traveling path 54 of the mover as shown in FIG. The six stator coils 16a and 16a ', 16b and 16b', 16c and 16c '
Are connected in series as shown in FIG. 3 and are connected to the switch circuit 20 in a three-phase star connection. As shown in FIG. 1, the conductive portion α of each stator coil and the core portion β are formed to have a uniform width, and a conductive portion α is provided between one stator coil and an adjacent stator coil. 1 /
There is an interval of length corresponding to three. On the other hand, the width of each permanent magnet 44 of the mover 40 is formed uniformly with the width of the conductive portion α and the core portion β of the stator coil. Each of the magneto-sensitive elements 14a, 14b, 14c of the sensor unit 14
Is an element that is sensitive to the detection magnet 48, that is, the mover magnet 44. For example, a Hall element is used. The interval between the magneto-sensitive elements 14a, 14b, 14c is set to 1.5 times the width of the permanent magnet.

A detection signal from each of the magnetic sensing elements 14a, 14b, 14c of the sensor unit 14 when the movable element 40 is detected is input to the OR circuit 22. The OR circuit 22 applies an output to the switch circuit 20 in response to this input.
As a result, the switch circuit 20 switches the coil plate 16A to a state where it can be energized. That is, the switch circuit 20
Are the lines 20a, 2a to the stator coils 16a, 16b
0b and the power bus line 18, the relay having contacts 20 a ′ and 20 b ′ interposed between the contacts 20 a ′ and 20 b ′ according to an output from the OR circuit 22.
To the connected state. Thereby, the coil plate 16A is connected to the power bus line 18 side.

A coil unit 12A and a coil unit 12B having the same configuration as the coil unit 12A shown in FIG.
12C is connected by a required length along the traveling path 54 of the mover as described above with reference to FIG. 2, and in this connection, the sensor bus line 17 and the power bus line 18 are connected.
Are connected to each other between the adjacent coil units 12A, 12B, and 12C.

The control unit 30 for controlling the mover 40 includes a control circuit 34 and a transistor circuit 36. The control circuit 34 controls the mover 40 and the coil plate 16A or the coil plate 16A based on a detection signal from the sensor unit 14. A drive signal is supplied to the transistor circuit 36 by determining a relative position with respect to 16B and 16C. Transistor circuit 36
Are six transistors Tra, T based on the drive signal.
rb, Trc, and Tra ', Trb', Trc 'are turned on and off, and each stator coil 16 of the coil plate 16A is turned on.
a, 16b, 16c, 16a ', 16b', 16c 'or the stator coils of the coil plates 16B, 16C are excited. The transistors Tra, Trb, Trc, and Tra ', Trb', Trc 'and the stator coils 16a, 16b, 16c and 16a' of the coil plate 16A, 1 '
The relationship of the excitation phase with 6b'16c 'is determined one-to-one for each operation direction of the mover 40. This is the same for the coil plates 16B and 16C. The connection of the control unit 30 to the stator 10 is performed by connecting the sensor bus line 17 and the power bus line 18 of the coil unit 12A provided at the end to the control unit 30 side.

Next, the operation of the linear motor according to the above configuration will be described. In a state where the control circuit 34 starts the mover 40, the mover 40 is located on the leftmost end (starting end) of the stator 10 on the low-speed coil unit 12A. The magnetic force of the detection magnet 48 of the mover 40 is sensed by each of the magnetic sensing elements 14a, 14b, and 14c of the sensor unit 14 of the coil unit 12A, and a detection signal is sent to the control circuit 34 and the OR circuit 22 side. doing. The OR circuit 22 sends a high-level signal to the switch circuit 20 in response to this. As a result, the switch circuit 20
The contact portions 20a 'and 20b' are connected, the three-phase star connection is closed, and the power bus line 18 is connected to the stator coil 16a.
To 16c 'so that the current can be supplied. On the other hand, based on the detection signal sent to the control circuit 34 via the sensor bus line 17, the control circuit 34 detects the relative positions of the mover magnet 44 and the stator coils 16a to 16c '. Based on this information, the control circuit 34 determines the excitation phase and determines the transistors Tra, Trb, Trc,
Then, by turning on Tra ', Trb', and Trc 'to excite the stator coils 16a to 16c', a thrust based on the Fleming left hand rule is applied to the mover magnet 44 to start the movement.

When starting the mover 40, the mover 4
Since the speed of 0 is zero, each of the stator coils 16a to 16
The back electromotive force Vb of c 'becomes zero. However, as described above, the coils 16a to 16c 'are wound with many thin coil wires (i.e., have a high resistance value) (i.e., have a long coil wire length). The coil current (rush current) represented by I = [V−Vb] / R mentioned in the description of the technology is suppressed by the value of the resistance value R,
In the stator coils 16a to 16c ', current is not wasted more than necessary, and the temperature does not become abnormally high.

When the mover magnet 44 sequentially corresponds to the stator coils 16a to 16c 'of the adjacent coil unit 12A as the mover 40 moves, the sensor unit 14
Responds to the magnetic force of the detection magnet 48 and sends out a detection signal to the control circuit 34 and the OR circuit 22 side. OR circuit 22
Sends a high-level signal to the switch circuit 20 in response to this. As a result, the adjacent coil units 12
The switch circuit 20 of A enables power to be supplied from the power bus line 18 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 17, the control circuit 34
And the relative positions of the stator coils 16a to 16c 'are detected. Based on these information, the control circuit 34
4 and the stator coils 16a to 16c ', the excitation phase is sequentially determined along with the movement of the mover 40, and the transistors Tra, Trb, T of the transistor circuit 36 are determined.
By selectively turning on rc and Tra ', Trb', and Trc 'to excite the stator coils 16a to 16c', a thrust is continuously applied to the mover magnet 44.

When the speed of the mover 40 increases and reaches the medium-speed coil unit 12B shown in FIG. 2, since the speed of the mover 40 is a medium speed, each of the stator coils 16d to 16f 'is fixed.
, A moderate back electromotive force Vb is generated. As described above, in the coils 16d to 16f ', a coil wire having a medium thickness (that is, a medium resistance value) is wound around the medium (that is, the number of turns N is medium). [V-Vb] /
The coil current represented by R is appropriately suppressed by the medium resistance value R, and the thrust represented by T∝NI also increases to a suitable value by the medium number of turns N,
Accelerate smoothly.

Further, when the speed of the mover 40 increases and reaches the high-speed coil unit 12C shown in FIG. 2, the maximum back electromotive force Vb is applied to each of the stator coils 16g to 16i 'because the speed of the mover 40 is high. Occur. However, as described above, since the coils 16g to 16i 'have a small amount of thick coil wire (small resistance) wound (minimum coil inductance L), the coil current represented by I = [V-Vb] / R Is not greatly limited by the resistance value R, and Vb
The back electromotive force Vb represented by ∝vL is unlikely to increase, and the speed saturation point due to the back electromotive force Vb increases. Therefore, the mover 40 can reach a high speed in the high-speed coil unit 12C.

FIG. 2 shows the left stroke end (start end) of the stator 10, and the stroke end (end) located on the right side of FIG. 2 is not shown. A medium-speed coil unit 12B (not shown),
The low-speed coil unit 12A is arranged, and here the mover 40 is decelerated. The linear motor of this embodiment stops the mover 40 at the right stroke end, and then drives the mover 40 again starting from the right stroke end toward the left stroke end shown in FIG.

The relationship between the speed and the current of the linear motor of this embodiment will be described in further detail with reference to FIG. Figure
4 (A) shows the relationship between the position of the linear motor and the operating speed. In the figure, the chain line indicates the low-speed coil unit 12A.
Operating speed when the stator 10 is constituted only by the medium speed coil unit 12B, the dashed line indicates the operating speed when the stator 10 is constituted only by the medium speed coil unit 12B, and the solid line indicates the operating speed by the high speed coil unit 12C. I have. As it can be seen from FIG. 4 (A), the linear motor of the present embodiment drives the movable element 40 at a high speed by the high-speed coil unit 12C. Figure
4 (B) shows the relationship between the moving distance of the linear motor and the coil current. Similarly to FIG. 4 (A), the chain line indicates the coil current when the stator 10 is constituted only by the low-speed coil unit 12A. As can be seen from FIG. 4 (B), the in this embodiment, the coil current is also growing speed can be driven at high speed the mover 40 because it does not decrease.

As described above, the energization of the switch circuit 20 is performed for each coil unit through which the mover 40 passes. That is, in the coil unit through which the mover 40 has passed, or in the coil unit before the mover 40, the switch circuit 20 is turned off, thereby preventing power consumption. That is, a method of energizing all the stator coils of the stator (entire area energization)
However, power consumption is kept small. This embodiment requires high speed, that is, is adopted in a linear motor having a long stator, so that power consumption can be suppressed by selectively energizing the stator coil,
As described above, the power consumption of the mover at low speed is reduced to improve energy efficiency.

In the embodiment, for example, when a vehicle is transported on a main transport line of about several hundred meters and parts to be assembled to the vehicle are transported by a plurality of sub-transport lines of about 5 m, the sub-transport is performed. It can be suitably applied for driving a line. That is, since the speed of the linear motor can be increased (about 5 m / sec), parts can be sent in a short time even on a long conveyance path of 5 m.

In this embodiment, the desired coil units 12A and 12A are adjusted in accordance with the speed required for the conveying path.
B and 12C can be appropriately selected. For example, a required number of low-speed coil units 12A are connected to a portion where the mover is to be sent while suppressing the speed. In the above-described example, the linear motor is reciprocated, that is, an example in which the linear motor is stopped only at both stroke ends is described. Medium-speed coil unit 12B and low-speed coil unit 1
By arranging 2A, it is possible to prevent waste of current at the intermediate stop.

In the above-described embodiment, three types of coil units, the low-speed coil unit 12A, the medium-speed coil unit 12B, and the high-speed coil unit 12C, are provided. It is also possible to configure the stator 10 with different types. On the contrary, in addition to the medium-speed coil unit 12B, a medium-low speed coil unit and a medium-high speed coil unit are provided. Can also be smoothed.

As described above, according to the embodiment, by changing the coil inductance of the stator coil, the mover can be driven at a high speed with the power supply voltage kept constant, and the loss of the mover at a low speed can be achieved. it is possible small Kusuru. Further, when the conventional linear motor is set for high speed, the size of the linear motor is increased in order to increase heat dissipation and insulation resistance so as to withstand a large current flowing through the stator coil at low speed. Since heat generation at low speed is low, a high-speed linear motor can be formed in a small size. Further, since the current at a low speed is small, the capacity of the power supply can be reduced.

The linear motor of the embodiment has an advantage that the structure is simple and can be constructed at low cost.

In the above-described embodiment, the stator is formed by connecting the coil units. Alternatively, a linear motor may be formed by an integrally formed stator. Further, in the above-described embodiment, a description has been given by taking as an example a magnet movable DC linear motor in which permanent magnets are arranged on the mover side, but the present invention is applied to a linear motor in which coils are also arranged on the mover side. It goes without saying that you get it. Furthermore, in the above-described embodiment, an example was given in which only the stator coil at a position corresponding to the mover is selectively energized. However, the present invention can be applied to a linear motor in which the entire stator is energized. it can.

[0055]

As described above, the linear motor of the present invention can drive the mover at high speed while keeping the power supply voltage constant, and can reduce the loss of the mover at low speed. Further, since the loss at low speed is small and the heat generation is low, it is possible to form a high-speed linear motor in a small size. Further, since the current at low speed is small, the power supply capacity can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a linear motor according to one embodiment of the present invention.

FIG. 2 is a perspective view of the linear motor shown in FIG.

FIG. 3 is a circuit diagram showing an assembled state of a stator coil according to the embodiment.

FIG. 4 shows the speed and coil of the linear motor according to the embodiment .
FIG. 4 is a diagram illustrating a relationship between a current and a position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stator 12 Coil unit 14 Sensor unit 18 Power bus line 20 Switch circuit 30 Control unit 40 Mover

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-184120 (JP, A) JP-A-47-32108 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02K 41/02-41/035

Claims (3)

(57) [Claims] 1. A linear motor having a mover and a stator having a plurality of stator coils arranged therein, wherein a stator coil having a small number of turns is arranged on the stator at a position where the mover operates at a high speed. And a stator coil having a large number of turns arranged at a position where the mover is at a low speed. 2. The method according to claim 1, wherein a thick coil wire is used for the stator coil having a small number of turns, and a thin coil wire is used for the stator coil having a large number of turns.
Linear motor. 3. A stator coil having an intermediate number of turns is arranged between the stator coil having a small number of turns and the stator coil having a large number of turns of the stator. 2 linear motor.