JP2005086873A - Shaft type linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft type linear motor capable of stopping a moving member without the need of power supply just before stopping, effectively using energy when a liner motor moving member reciprocates. <P>SOLUTION: A linear motor moving member 2 of the shaft type linear motor reciprocates along a linear motor stator 1 on the basis of a linear motor drive mechanism 3 composed of the shaft type linear motor stator 1 where a plurality of magnets N, S to N, S are arranged and the cylindrical linear motor moving member 2 in which the linear motor stator 1 is movably inserted. A control means 8 brakes by reducing a thrust force of the linear motor moving member 2, by controlling the air pressure in a cylinder 4 on the reciprocating side of the linear motor moving member 2 on the basis of cutting off of a supplied current when the supply of a current to the linear motor moving member 2 is cut off. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a shaft-type linear motor, and more particularly to a shaft-type linear motor that stops the mover without requiring power supply immediately before the stop by effectively using energy when the linear motor mover moves back and forth. Is.

  2. Description of the Related Art Conventionally, a rotary motor including a magnet as a rotor and a coil as a stator arranged so as to surround the outer periphery thereof is well known. Since this rotary motor has a large regenerative power, if the supply current is cut off immediately before stopping the operation (just before the rotor stops), the regenerative power does not consume additional power due to the large regenerative power, that is, without supplying power from the power source. Operation can be stopped (rotor stopped).

  On the other hand, a linear motor driving mechanism comprising a shaft type linear motor stator constituted by arranging a plurality of magnets and a cylindrical linear motor movable element movably inserted through the linear motor stator, the linear motor driving mechanism is used. A shaft type linear motor in which a motor movable element moves forward and backward along the linear motor stator is also well known. However, the regenerative power of this shaft type linear motor is smaller than that of the rotary motor. Therefore, even if the supply current is cut off immediately before the operation is stopped (just before the linear motor mover is stopped), the operation is stopped by the regenerative power. (The linear motor mover cannot be stopped), and conversely, power must be supplied from the power source.

  This is because, in a rotary motor and a shaft type linear motor with the same output, in the case of a rotary motor, the amount of electric wire of the coil provided in the rotor is small, so the DC resistance is small, and the self-inductance is smaller than this small DC resistance. Therefore, it is easy to generate electromotive force due to electromagnetic induction. For this reason, the regenerative electric power by self-inductance becomes large, and an operation | movement can be stopped (rotor is stopped), without supplying electric power from a power supply. On the other hand, in a shaft type linear motor in which the mover is provided with a coil, the amount of electric wire of the coil provided in the rotor of the rotary motor is increased by several tens of times and the direct current resistance is increased by several tens of times. Thus, the self-inductance is considerably smaller than the self-inductance of the rotary motor. In other words, in a shaft type linear motor, even if the supply current is cut off immediately before the linear motor mover stops and the power supplied when the linear motor mover is moved is recovered by the coil (self-inductance) of the mover, the self-inductance is not generated. Because it is small, it can be recovered, but it is very small, and when it flows through the coil, it will be consumed by being converted to heat. If power is not supplied from the power supply, the moving linear motor mover is stopped by inertia It is not possible.

  Now, the rotary type motor and the shaft type linear motor are replaced with the equivalent circuit shown in FIG.

First, the impedance Zr of the rotary motor is calculated.
Time constant τ = 8.7msec
U-V phase resistance Rr = 0.45Ω
U-V phase inductance (calculated value) Lr = 3.9 mH
Sine wave frequency f = 238 Hz of voltage applied to the motor when moving at an axial speed of 1.3 m / sec, where ω = 2πf (ω: angular frequency rad / sec)
Under the above conditions, the impedance Zr of the rotary motor is calculated by the following equation (1).

Next, the impedance Zr of the shaft type linear motor is calculated.
Time constant τ = 1.7msec
U-V phase resistance Rr = 15.0Ω
U-V phase inductance (calculated value) Ls = 25.5 mH
Applied voltage frequency to the motor when moving at an axial speed of 1.3 m / sec f = 11 Hz
Under the above conditions, the impedance Zr of the shaft type linear motor is calculated by the following formula 2.

  Comparing the impedances calculated by the above formula, it can be seen that the resistance element and the coil element are affected, and the coil element is significantly different. If the inductance of the shaft type linear motor is also increased, the power supply when the supply current is cut off immediately before the stop of operation (just before the stop of the linear motor mover) is kept small, and the operation is stopped by regenerative power (the linear motor mover) However, in practice, it is impossible to change the number of turns of the coil even if it is considered to increase the inductance, and an attempt is made to increase the applied voltage frequency f. However, the magnetic pole pitch is narrowed, and the internal magnetic flux of the magnet is increased. As a result, the magnetic flux that can be used in the linear motor is reduced and the thrust is reduced.

  That is, in the shaft type linear motor, the supply current is cut off immediately before the linear motor mover stops, and the self-inductance does not occur even when the electric power supplied when the linear motor mover is moved is recovered by the coil (self-inductance) of the mover. Due to the small size, there is a problem that the linear motor movable element moving by inertia cannot be stopped unless power is supplied from the power source.

  The present invention solves such a problem, and by effectively using the energy when the linear motor movable element moves forward and backward, the movable element can be stopped without the need for power supply immediately before stopping. It aims at providing a shaft type linear motor.

  In order to achieve the above object, a shaft type linear motor according to the present invention includes at least the linear motor movable element housed in a cylinder capable of moving the linear motor movable element forward and backward by a predetermined stroke amount. It is characterized by comprising braking means for controlling the fluid pressure in the cylinder on the advancing / retreating movement side of the linear motor movable element when the supply current to the linear motor movable element is interrupted to reduce the thrust of the linear motor movable element for braking. .

  In the present invention, when the supply current to the linear motor movable element is interrupted, the fluid pressure in the cylinder on the advancing / retreating side of the linear motor movable element is controlled to reduce the thrust of the linear motor movable element for braking. Thus, the linear motor movable element can be stopped without the need for power supply immediately before the stop.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a cylinder according to an embodiment of the present invention with the cylinder removed, FIG. 2 is a longitudinal side view of FIG. 1, and FIG. 3 is an overall configuration diagram showing an embodiment of the present invention. 1 and 2, the shaft type linear motor includes a round shaft type linear motor stator 1 and a cylindrical linear motor movable element 2.

  A round shaft type linear motor stator 1 is formed by connecting a plurality of magnets (permanent magnets) N, S... In the axial direction (advancing and retreating direction of the linear motor movable element 2). The cylindrical linear motor movable element 2 is inserted in the cylindrical body 1A of the linear motor stator 1 so as to be movable along the linear motor stator 1 in the axial direction (movable linear motor). The linear motor stator 1 and the linear motor are provided with a plurality of electromagnetic coils 2A arranged in the direction of movement of the child 2) and a cylindrical body 2B made of a magnetic material incorporating the plurality of electromagnetic coils 2A. The mover 2 constitutes a linear motor drive mechanism 3.

  As shown in FIG. 3, the linear motor stator 1 and the linear motor mover 2 are hermetically housed in a cylinder 4 that can move the linear motor mover 2 forward and backward by a predetermined stroke amount. The cylinder 4 is preferably made of a magnetic material. In addition, the linear motor movable element 2 is arranged between the inner peripheral surface of the linear motor movable element 2 and the outer peripheral surface of the linear motor stator 1 with the first seal ring 5 interposed between the linear motor movable element 2 and the linear motor movable element 2. The stator 1 can be moved forward and backward as a guide, and a second seal ring 6 is interposed between the inner peripheral surface of the cylinder 4 and the outer peripheral surface of the linear motor movable element 2 to maintain airtightness. In this state, the linear motor movable element 2 is configured to move forward and backward in the cylinder 4.

  Sealing plate 4A sealing one end (front end) in the axial direction of cylinder 4 is provided with intake / exhaust holes 5A and sealing the other end (rear end) in the axial direction. The plate 4B is provided with intake and exhaust holes 5B. The third seal ring 7 is interposed between the inner peripheral surfaces of the sealing plates 4A and 4B and the outer peripheral surface on the shaft end side of the linear motor stator 1 to maintain airtightness.

  On the other hand, the shaft type linear motor brakes by controlling the air pressure in the cylinder 4 on the moving side of the linear motor movable element 2 (solid arrow in FIG. 3) to reduce the traveling thrust of the linear motor movable element 2. In addition, there is provided braking means 8 for controlling the air pressure in the cylinder 4 on the moving side of the linear motor movable element 2 in the backward direction (broken arrow in FIG. 3) to reduce the backward thrust of the linear motor movable element 2 and brake it. Yes.

  The braking means 8 is derived from the P1 position where the supply current to the linear motor movable element 2 is cut off before the linear motor movable element 2 moves forward in the direction of the solid arrow and reaches the stroke front end PX1, and the electromagnetic valve Mg1 A forward-side first exhaust passage 8A interposed between the front-end sealing plate 4A corresponding to the front-stroke end PX1 and a forward-side first exhaust passage 8A in which an electromagnetic valve Mg2 and a throttle valve STV1 are interposed in series. 2 The intake passage 8B and the intake passage 8C and the linear motor movable element 2 which are led out from the sealing plate 4A at the front end and are provided with the electromagnetic valve AMg1 retreat in the direction of the broken line arrow and reach the stroke rear end PX2. The first exhaust passage 8D on the reverse side, which is derived from the position P2 where the supply current to the linear motor movable element 2 is cut off in front, and the electromagnetic valve Mg3 is interposed, and the rear end corresponding to the stroke rear end PX2 Derived from the stop plate 4B, the retraction-side second exhaust passage 8E in which the electromagnetic valve Mg4 and the throttle valve STV2 are connected in series, and the rear end sealing plate 4B are led out through the electromagnetic valve AMg2. And an intake passage 8F provided.

  The shaft type linear motor is configured such that the electromagnetic valve Mg1, the electromagnetic valve Mg2, and the electromagnetic valve Mg2 of the braking unit 8 are based on control signals output from the controller 10 at the P1 position and the P2 position where the supply current to the linear motor movable element 2 is interrupted. The solenoid valve AMg1, the solenoid valve Mg3, the solenoid valve Mg4, and the solenoid valve AMg2 are controlled to open and close.

  In the above-described configuration, the linear motor is driven from the state in which the rear end of the linear motor movable element 2 is in contact with the inner surface of the sealing plate 4B at the rear end, that is, the linear motor movable element 2 is stopped at the rear end of the stroke. When the linear motor movable element 2 moves forward in the direction of the solid arrow by the mechanism 3, the solenoid valve Mg1, the solenoid valve AMg1, the solenoid valve Mg3, and the solenoid valve AMg2 are opened by the control signal output from the controller 10, respectively. Smooth advance of the linear motor movable element 2 is allowed by closing the valve Mg2 and the electromagnetic valve Mg4.

  When the linear motor movable element 2 moves forward and reaches the P1 position where the supply current to the linear motor movable element 2 before reaching the stroke front end PX1 is interrupted, the controller 10 controls based on the interruption of the supply current. A signal is output, the electromagnetic valve Mg2 is opened, and the electromagnetic valve Mg1 and the electromagnetic valve AMg1 are closed. As a result, the amount of air exhausted between the P1 position and the stroke front end PX1 is suppressed by the throttle action of the throttle valve STV1, and the air pressure is controlled, so that the thrust of the linear motor movable element 2 is reduced and braking is performed. can do.

  On the other hand, from the state in which the front end of the linear motor movable element 2 is in contact with the inner surface of the sealing plate 4A at the front end, that is, the linear motor movable element 2 is stopped at the front end of the stroke, the linear motor driving mechanism 3 causes the linear motor to move. When the mover 2 moves backward in the direction of the broken line arrow, the solenoid valve Mg1, the solenoid valve AMg1, the solenoid valve Mg3, and the solenoid valve AMg2 are opened by the control signal output from the controller 10, respectively. Smooth receding of the linear motor movable element 2 is allowed by closing the valve of Mg4.

  When the linear motor movable element 2 moves backward and reaches the P2 position where the supply current to the linear motor movable element 2 just before reaching the rear end PX2 of the stroke is cut off, the controller 10 is based on the interruption of the supply current. A control signal is output, the electromagnetic valve Mg3 is opened, and the electromagnetic valve Mg3 and the electromagnetic valve AMg2 are closed. As a result, the amount of air exhausted between the position P2 and the rear end PX2 of the stroke is suppressed by the throttle action of the throttle valve STV2, and the air pressure is controlled, so that the thrust of the linear motor movable element 2 is reduced and braking is performed. can do.

  Thus, when the supply current to the linear motor movable element 2 is interrupted, the shaft type linear motor according to the present invention reduces the air pressure in the cylinder 4 on the advancing / retreating side of the linear motor movable element 2 based on the interruption of the supply current. Since the braking is performed by reducing the thrust of the linear motor movable element 2 by controlling, the linear motor movable element 2 can be stopped without requiring the power supply immediately before the stop.

  The shaft type linear motor has an electrical characteristic in which the current flowing through the electromagnetic coil 2A of the linear motor movable element 2 instantaneously increases when the supply current is interrupted. Then, the air pressure may be controlled as described above by the control signal that is input to the controller 10 and output from the controller 10 based on this, and the thrust of the linear motor movable element 2 may be reduced to perform braking.

  Further, as shown by a two-dot chain line in FIG. 3, an axial through hole 11 is provided in the linear motor stator 1, and the first exhaust passage 8 </ b> A on the advancing side and the first retreat side on the one end of the through hole 11. The effect of air-cooling the linear motor stator 1 can be expected by connecting the exhaust passage 8D.

It is a perspective view which removes and shows the cylinder of one embodiment of the present invention. It is a vertical side view of FIG. It is a whole lineblock diagram showing one embodiment of the present invention. It is the equivalent circuit diagram which replaced the motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear motor stator 2 Linear motor mover 3 Linear motor drive mechanism 4 Cylinder 8 Control means

Claims (1)

The linear motor movable element comprises a shaft type linear motor stator configured by arranging a plurality of magnets and a linear motor movable mechanism that is movably inserted through the linear motor stator. In a shaft type linear motor that moves back and forth along the linear motor stator,
At least the linear motor mover is housed in a cylinder that can move the linear motor mover forward / backward by a predetermined stroke amount, and when the supply current to the linear motor mover is interrupted, the linear motor mover moves forward / backward. A shaft-type linear motor comprising braking means for controlling the fluid pressure in the cylinder to reduce the thrust of the linear motor mover and braking.

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