JPH0797897B2 - Linear motor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a linear motor used for transportation.

[Prior Art] Recently, a linear motor has been used for conveyance, and as a linear motor of this type, a current is selectively supplied to a plurality of coils according to the movement of a movable block. For example,
In a moving coil type linear motor having a mover block of three phases, as shown in FIG. 9, coils of the same winding specifications are used as the coils 3a to 3c of the respective phases of the mover block. One ends of the phase coils 3a to 3c are commonly connected, power is supplied between any two ends of the coils 3a to 3c, and a current is always passed through the two phase coils 3.

[Problems to be Solved by the Invention] However, a plurality of coils 3 having the same winding specifications as described above are provided.
10 is a multi-phase linear motor using the
As shown in (d), when a current is constantly applied to the coils 3 of two phases (each phase is called U, V, W phase), FIG.
As shown in (4), there is almost no change in the total motor current that indicates the moving speed of the mover block. Moreover, since the moving coil type linear motor has a power supply circuit for supplying power to the coils 3a to 3c on the side of the stator block separated from the mover block, it detects the current individually flowing in any of the coils 3a to 3c. This is difficult, and as a result, the advancing speed of the linear motor can only be detected from the output current of the power feeding circuit, that is, the total motor current. Therefore,
If the change in total motor current is small as described above,
It is difficult to detect the traveling speed of the linear motor from this motor current. For example, the current supplied to the linear motor is varied by the power supply circuit to control the speed, or the speed of the linear motor is detected to control the speed constant. However, there is a problem that it is difficult to control the speed.

The present invention has been made in view of the above points, and an object of the present invention is to provide a linear motor capable of performing speed control by detecting the speed from the total motor current.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes coils of a plurality of phases, and moves the mover block by switching a current to each of the coils of the same number of phases to move and move the mover block. A multi-phase linear motor that outputs a signal corresponding to the moving speed of the child block and feedback-controls the energy supplied to the coil by the power feeding circuit so that the moving speed of the mover block is stabilized based on this signal. , The coil resistance of any one phase coil is made different from the coil resistance of the other phase coil, and the cycle of the change of the total motor current flowing through the coil is output to the power supply circuit as the above signal corresponding to the moving speed of the mover block. It is characterized by doing.

[Operation] According to the present invention, with the configuration described above, since a clear change representing the traveling speed appears in the total motor current, this motor current is used as a signal corresponding to the traveling speed of the mover block. The traveling speed of the mover block can be stabilized by adjusting the energy supplied from the power supply circuit to the coil.

[Embodiment] FIGS. 1 to 8 show an embodiment of the present invention. The linear motor of this embodiment is of a moving coil type, and has a structure in which a mover block B slides along a stator block A.

The stator block A includes a long base 7 having an L-shaped cross section, a long permanent magnet 1 arranged over the entire length of the center of a horizontal piece 7a of the base 7, and a vertical piece 7b of the base 7. The power supply board 5 is mounted on the wall surface and supplies power to the coil 3 of the mover block B.

As shown in FIG. 4, the permanent magnet 1 has a flat plate shape and is alternately magnetized into N poles and S poles at a constant pitch in the longitudinal direction, and also in the thickness direction as shown in FIG. As shown in c), the north pole and the south pole are magnetized. The permanent magnet 1 is attached to the horizontal piece 7a of the base 7 by adhesion or caulking. The length of a pair of magnet pieces consisting of the N pole and the S pole in the longitudinal direction of the permanent magnet 1 is L as shown in FIG.

As shown in FIG. 5 (a), the power supply board 5 has an insulating portion 5c that vertically meanders at regular intervals in the central portion, and the upper and lower portions separated by the insulating portion 5c are used as conductor portions 5a and 5b. is there.
Then, a positive voltage is applied from the upper conductor portion 5a to the coil 3 of the mover block B, which will be described later, and a negative voltage is applied to the coil 3 from the lower conductor portion 5b. Here, each conductor part 5a, 5
The width of the portion of b that protrudes toward the center is formed to be L / 3, and the width of the insulating portion 5c located between the conductor portions 5a and 5b is formed to be L / 6.

The mover block B has an iron core 2 formed by stacking substantially U-shaped yokes, a coil 3 wound around the iron core 2, and one end of the coil 3 is connected to the mover block B to slide on the power supply board 5. It is a three-phase structure in which three electromagnets 8 each of which is in contact with the brush 4 are arranged in a row. The other end of the coil 3 is commonly connected as shown in FIG. The length of each electromagnet 8 along the longitudinal direction of the base 7 is set so as not to exceed L / 3. That is, the length along the longitudinal direction of the stator block A of the iron core 2 is
When l ₁ is set, l ₁ <L / 3, and when the coil 3 is wound, the length of the electromagnet 8 does not exceed the above L / 3. The distance between the brushes 4 provided for each electromagnet 8 and attached to the mover block B by the insulating plate 20 is L /
3 and these brushes 4 come into contact with the central position of the power supply board 4 shown by the alternate long and short dash line in FIG.

As shown in FIG. 3, the stator block A and the mover block B are arranged in a rectangular tubular guide rail 6, and a guide groove 9 is formed in the center of the lower surface of the guide rail 6 along the longitudinal direction. It is set up. A movable body block B is integrally fixed with a connecting body 10 for connecting conveyed objects such as ornaments,
The movable piece block B is housed in the guide rail 6 by projecting the connecting piece 10 a protruding from the connecting body 10 from the guide groove 9 of the guide rail 6. It should be noted that rollers 11 for smoothing the movement of the mover block B are provided on both sides of the coupling body 10, and the iron core 1 of the mover block B is attached to the base body 7.
A slip plate 12 having a small coefficient of friction is attached to a portion slidingly contacting with. The holes 16 formed in the connecting piece 10a are for connecting the objects to be conveyed.

With this linear motor having the above-described structure, a constant current is always supplied from the power feeding substrate 5 to any two phases of the three-phase coils 3a to 3c, and a propulsive force in a certain direction is obtained by the magnetomotive force generated at this time. The mover block B advances. When moving the mover block B in the opposite direction, the positive and negative voltages of the conductor portions 5a and 5b of the power supply board 5 may be reversed.

By the way, in the present embodiment, the winding specification of the coil 3 of the one-phase electromagnet 8 among the three-phase electromagnets 8a to 8c is made different from the winding specification of the coil 3 of the other-phase electromagnet 8. In the following description, the case where the winding specifications of the coil 3b of the electromagnet 8b in FIG. 2 are different will be described. In the following description, the electromagnet 8a is referred to as the U phase, 8b is referred to as the V phase, and 8c is referred to as the W phase, and each phase is supplied with electric power as shown in FIGS. . In this case, specifically, the U-phase and W-phase coils
When the coil resistance of 3a and 3c is 2Ω, the coil resistance of the V-phase coil 3b is 8Ω, and the driving power supplied from the power supply board 5 is 24V, power is supplied to the U-V phase and the V-W phase. The motor current I ₁ is I ₁ = 24 / (2 + 8) = 2.4 (A), and the motor current I ₂ when power is supplied to the U-W phase is I ₂ = 24 / (2 + 2) = 6. (A) That is, as described above, by making the coil resistance of the coil 3 of any one of the three phases larger than the coil resistance of the coil 3 of the other phase, the motor current changes according to the traveling speed. Become. Therefore, by detecting this periodic change, it becomes possible to control the speed of the linear motor.

FIG. 7 shows an example of a power supply circuit that controls the speed of the linear motor. In this power supply circuit, the linear motor M
The traveling speed of the linear motor M is detected from the periodical change of the current flowing in the linear motor M, and a signal corresponding to the detected output is fed back to the control unit 14 of the switching power supply circuit 13 to keep the linear motor M constant at the set speed. Is equipped with a constant speed control means 17 for driving the current transformer T ₂ , the waveform shaping circuit 1
5, the constant speed control means 17 in the frequency / voltage conversion circuit (hereinafter, referred to as FV conversion circuit) 16 and the differential amplifier circuit A ₁ .
Is configured. Current transformer T ₂ are Yes connected in series with the linear motor M to the output of the switching power supply circuit 13, the linear motor M by the current transformer T ₂
Changes in the current flowing through the motor, that is, the linear motor M
To detect the speed of. The current I _M flowing through the linear motor _M is shown in FIG. ₂ of this current transformer T 2
The next output V ₁ has the signal waveform shown in FIG. This 2
When the waveform shaping circuit 15 including the comparator A ₂ , the diode D ₅ , the resistor R ₃ and the reference voltage E ₂ performs waveform shaping on the next output V ₁ , the waveform shaping output V ₂ shown in FIG. 8C is obtained. Then, the FV conversion circuit 16 converts the waveform shaping output V ₂ into a voltage signal V _F according to the speed shown in FIG. 8 (d). This voltage signal V ₃ is input to the differential amplifier circuit A ₁ and differentially amplified with the speed setting voltage E ₁ which is adjusted when the speed of the linear motor M is varied, and this differential amplified output is controlled. Input to the control terminal of the section 14. In the control unit 14 to which the differential amplified output is input, the duty of the output is changed according to the differential amplified output to change the speed of the linear motor M to the speed setting voltage.
The switching element Q ₁ is turned on and off so that the speed set by E ₁ is kept constant. That is, in this power supply circuit, the constant speed control means 17 detects the speed of the linear motor M, and a signal corresponding to this speed is fed back to the control unit 14 of the switching power supply circuit 13 to control the linear motor M at a constant speed. I am doing it.

In the above description, the case of constant speed control has been described, but it goes without saying that the present invention can also be applied to speed control for variably adjusting the traveling speed, and the present invention may be applied to a fixed coil type linear motor.

[Effects of the Invention] As described above, the present invention makes the coil resistance of any one-phase coil different from the coil resistance of the other-phase coil so that the cycle of the change in the total motor current flowing through the coil can be set to the mover block. It outputs to the power feeding circuit as a signal corresponding to the traveling speed, and the power feeding circuit feedback-controls the energy supplied to the coil so as to stabilize the traveling speed of the mover block based on the signal. Since the traveling speed of appears in the change in the total motor current flowing through the coil, it is possible to use the motor current as a signal corresponding to the traveling speed of the mover block without adding a sensor for separately detecting the traveling speed. By adjusting the energy supplied from the power supply circuit to the coil, the traveling speed of the mover block can be stabilized. It has the advantage of saying.

[Brief description of drawings]

1 is a front view of an embodiment of the present invention, FIG. 2 is a perspective view of the same as above, FIG. 3 is a perspective view when a guide rail is provided, and FIG. 4 is a perspective view showing the structure of the main part of the same. 5 and FIG. 5 (a) are front views of the power feeding board, FIGS. 5 (b) and 5 (c) are explanatory views showing a driving state of the movable block by the power feeding board, and FIG. 6 is an operation explanation showing the motor current of the same. FIG. 7 is a circuit diagram of a power supply circuit, FIG. 8 is an operation explanatory diagram of the same as above, FIG. 9 is a coil wiring diagram, and FIG. 10 is a conventional motor current explanatory diagram. A is a stator block, B is a mover block, and 3a to 3c are coils.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukihiko Okamura 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) Reference JP-A-1-238451 (JP, A)

Claims (1)

[Claims] 1. A mover block is moved by switching a current to each of the coils of the same number of phases, and a signal corresponding to the moving speed of the mover block is output. Is a multi-phase linear motor in which the energy supplied to the coils is feedback-controlled by a power feeding circuit so that the traveling speed of the mover block is stabilized based on The linear motor is characterized in that it is different from the coil resistance of No. 1, and the cycle of change of the total motor current flowing through the coil is output to the power supply circuit as the above signal corresponding to the traveling speed of the mover block.