JP2011030368A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear actuator moving displacement of the linear actuator to a specified position at high speed even if a failure occurs. <P>SOLUTION: The linear actuator 1 is provided with an outer tube 2, a rod 3 which is inserted into the outer tube 2 so that it can freely move, a field 4 provided with a plurality of permanent magnets 5 and held by the outer tube 2 or the rod 3 and a coil group C formed of a plurality of coils U1, U2, U3, V1, V2, V3, W1, W2 and W3, which confront with the field 4 and are held by the outer tube 2 and the other rod 3. The actuator generates thrust which relatively displaces the outer tube 2 and the rod 3 in an axial direction. An axial direction range where the coil group C is installed is made longer than an axial direction length of the field 4 and a short-circuiting means 7 short-circuiting the coils U1, V1 and W1 installed in a specified axial direction range L in a case of fault is arranged. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a linear actuator.

  Conventionally, as this type of linear actuator, for example, one that is embodied in a suspension device interposed between a vehicle body and an axle of a vehicle is known, and is inserted movably into an outer tube and an outer tube. Axially on a cylindrical core fixed in the outer tube with a rod to be held, a field magnet provided on the outer periphery of the rod with a plurality of annular permanent magnets, and a multi-phase coil facing the field And a coil group composed of a plurality of coils held side by side.

  In addition, each coil group includes three phases configured by connecting a plurality of coils in series, and one end of each of these three phases is Y-connected. A damping force to be suppressed is generated (see, for example, Patent Document 1).

  Furthermore, in this conventional linear actuator, when the power cable is disconnected, the other ends of each phase are connected by two relays, and one end of each phase is Y-connected. The coils of each phase form a closed circuit, and when the magnetic field fixed to the rod moves relative to the coil fixed to the outer tube, an electromagnetic force is generated so that the coil is induced to prevent the magnetic field from moving. Even when there is a disconnection, the damping force can be exerted.

JP 2003-223220 A

  By the way, when a linear actuator is used in an application for driving any member, for example, when used for driving a moving blade such as an aircraft ladder, aileron, elevator or flap, when a failure occurs in the linear actuator. In some cases, a member such as a moving blade is desired to be positioned at a previously specified position such as a neutral position.

  However, the conventional linear actuator is intended to be used as a shock absorber that is interposed between the vehicle body and the axle to generate a damping force. When a failure occurs, regardless of the positional relationship between the rod and the outer tube, Since a damping force is always generated over the entire length of the stroke, the relative position of the rod and outer tube (the displacement of the linear actuator) cannot be quickly returned to a specific position, and the displacement of the linear actuator can be reduced at a specific position. I can't hold it.

  Therefore, the present invention was devised to improve the above-described problems, and the object of the present invention is to provide a linear actuator that can quickly move the displacement of the linear actuator to a specific position even if a failure occurs. An actuator is provided.

  In order to achieve the above object, the problem solving means of the present invention includes an outer tube, a rod that is movably inserted into the outer tube, and a plurality of permanent magnets, and is held by one of the outer tube and the rod. In a linear actuator that includes a field and a coil group composed of a plurality of coils held on the other of the outer tube and the rod facing the field, and that generates a thrust that relatively displaces the outer tube and the rod in the axial direction. The axial range in which the coil group is installed is made longer than the axial length of the field, and short-circuiting means for short-circuiting the coil installed in the specific axial range at the time of failure is provided.

  According to the linear actuator of the present invention, when the field is in a predetermined axial range within the axial installation range of the coil group, the field is opposed to the short-circuited coil. Since the electromagnetic force is induced by the movement of the magnets with respect to the coil within the specific axial range and prevents the field movement, the rod will be braked against the outer tube, The rod can be positioned at a specific position with respect to the outer tube, the movement of the rod with respect to the outer tube can be suppressed, and the rod can be held at the specific position with respect to the outer tube.

  In addition, even if the rod deviates from the specific position with respect to the outer tube, the braking force does not work outside the specific position, and it expands and contracts freely. Therefore, returning to a specific position is not hindered.

  Therefore, even if a failure occurs, the displacement of the linear actuator can be quickly moved to a specific position, and this linear actuator can be used to return the displacement to a specific position and retain it as it is, specifically, For example, it is optimal for driving moving blades such as aircraft ladders, ailerons, elevators and flaps.

It is a cross-sectional view of the linear actuator in one embodiment. It is a circuit diagram in the linear actuator in one embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the linear actuator 1 according to an embodiment includes an outer tube 2, a rod 3 that is movably inserted into the outer tube 2, and a plurality of permanent magnets 5. The outer tube 2 is provided with a field 4 to be applied and three-phase coils U1, U2, U3, V1, V2, V3, W1, W2, and W3 of the U phase, the V phase, and the W phase. The coil group C is arranged and held in the axial direction via the core 6 and the short-circuit means 7 for short-circuiting the coils U1, V1, W1 installed in a specific axial range at the time of failure. Yes.

  In the linear actuator 1, the above-described coils U1, U2, U3, V1, V2, V3, W1, W2, and W3 are excited at an appropriate timing, whereby the rod 3 that holds the field 4 and The outer tube 2 that holds the coils U1, U2, U3, V1, V2, V3, W1, W2, and W3 can generate a thrust that relatively displaces in the axial direction.

  Hereinafter, each part of the linear actuator 1 will be described in detail. In this embodiment, the rod 3 is mounted on the outer periphery of the rod portion 3a, a guide portion 3b having a larger outer diameter than the rod portion 3a provided at one end of the rod portion 3a, and an outer tube. 2 and a slide ring 3c slidably in contact with the inner circumference.

  A plurality of, in this case, two annular permanent magnets 5 arranged in the axial direction are mounted on the outer periphery of the intermediate portion of the rod portion 3a. In the present embodiment, the permanent magnet 5 is mounted on the outer periphery of the rod portion 3a. However, the rod 3 may be hollow and the permanent magnet 5 may be accommodated in the rod 3.

  Each permanent magnet 5 is held on the rod 3 by being mounted on the outer periphery of the rod portion 3a as described above. One permanent magnet 5 has an N-pole on the inner peripheral side, an S-pole on the outer peripheral side, and the other The permanent magnet 5 is magnetized with the S-pole on the inner peripheral side and the N-pole on the outer peripheral side. When arranged in the axial direction, the N and S poles appear. Therefore, a magnetic field that acts on the coils U1, U2, U3, V1, V2, V3, W1, W2, and W3 is generated on the outer periphery of the rod 3 by the permanent magnets 5, and these permanent magnets 5 use linear actuators. 1 constitutes the field 4. The permanent magnet 5 has different magnetic poles on the inner and outer circumferences, but may be magnetized so that different magnetic poles appear in the axial direction.

  In the figure, two permanent magnets 5 are provided on the rod 3. However, as long as the linear actuator 1 can be driven, the number of installations is not limited to this.

  In this embodiment, the outer tube 2 has a bottomed cylindrical shape, and a cylindrical core 6 is mounted on the inner periphery. The rod 3 described above is movably inserted into the outer tube 2 and the core 6, and the outer periphery of the rod 3 is slidably supported by a cylindrical slide bearing 12 provided at the open end of the outer tube 2. It is supported. Further, the slide ring 3 c of the rod 3 is in sliding contact with a portion that is the inner periphery of the outer tube 2 and does not interfere with the core 6 even when the rod 3 and the outer tube 2 move relative to each other. That is, the rod 3 is supported with respect to the outer tube 2 by the slide bearing 12 and the guide portion 3b, and the shaft shake is prevented with respect to the outer tube 2, and the outer tube 2 and the rod 3 are smoothly relative to each other in the axial direction. It can be moved.

  A small-diameter portion 2b is provided on the inner circumference of the outer tube 2 and on the left side in FIG. 1, which is the inner side of the core 6, and the rod 3 is relatively displaced in the direction of retreating from the outer tube 2. When the right end in FIG. 1 of the guide portion 3b of the rod 3 and the left end in FIG. 1 of the small diameter portion 2b collide with each other, further extension of the linear actuator 1 is restricted. When the left end of FIG. 1 of the guide portion 3b and the inner surface of the bottom portion 2a collide with each other in the direction in which the linear actuator 1 enters, the further contraction of the linear actuator 1 is restricted.

  Thus, the stroke range of the rod 3 relative to the outer tube 2 is defined by the above structure, but within this stroke range, the core 6 is always positioned within the axial length range of the field 4 of the rod 3. It faces the field 4 and prevents the linear actuator 1 from being unable to generate thrust.

  Moreover, the outer end of the bottom portion 2a of the outer tube 2 is provided with an attachment portion 13 having an attachment hole, and the linear actuator 1 is connected to an external device via the attachment portion 13 and the attachment portion 3d of the rod 3. It can be attached.

  The core 6 accommodates the coils U1, U2, U3, V1, V2, V3, W1, W2 and W3, and is provided with a plurality of slots 6a arranged in the axial direction and a plurality of slots 6a provided between both ends and the slots 6a and 6a. The pole teeth 6b are provided.

  In this case, the core 6 configured in this way is cylindrical and has an inner circumference opposed to the field 4 of the rod 3, and the coils U1, U2, U3, V1, V2, V3, W1, W2, and so on. By exciting W3 and magnetizing the pole teeth 6b, the permanent magnet 5 in the field 4 of the rod 3 is attracted and repelled to generate a thrust that causes the outer tube 2 and the rod 3 to be displaced relative to each other in the axial direction. It has become. The core 6 does not necessarily have a cylindrical shape, and the field 4 held by the rod 3 does not form a magnetic field over the entire outer periphery of the rod 3 and does not generate a magnetic field in a direction facing the core 6. However, the permanent magnet 5 may be formed in a cylindrical or disk shape to generate a magnetic field on the outer periphery of the rod 3 and the core 6 may be formed in a cylindrical shape so as to surround the outer periphery of the rod 3. On the other hand, there is an advantage that the thrust does not change even if the rod 3 rotates in the circumferential direction. In this embodiment, the coils U1, U2, U3, V1, V2, V3, W1, W2, and W3 are attached to the core 6, but the core 6 is omitted and the coil is directly attached to the outer tube 2. U1, U2, U3, V1, V2, V3, W1, W2, and W3 can be mounted.

  The axial length of the coil group C composed of the coils U 1, U 2, U 3, V 1, V 2, V 3, W 1, W 2, W 3 is longer than that of the permanent magnet 5 constituting the field 4. That is, the axial range in which the coil group C is installed is longer than the axial length of the field 4.

  The coils U1, U2, U3, V1, V2, V3, W1, W2, and W3 are mounted in the slot 6a so as to surround the outer periphery of the rod 3, and in the illustrated case, the U phase, V It arrange | positions so that a phase and W phase may appear alternately.

  More specifically, in this embodiment, the coil group C includes a U-phase formed by connecting three coils U1, U2, and U3 in series and a V-phase formed by connecting three coils V1, V2, and V3 in series. Phase and three coils W1, W2, and W3 formed in series, so that the U-phase, V-phase, and W-phase coils appear in order in the axial direction, that is, If it demonstrates using FIG. 1, the coil U2, the coil V2, the coil W2, the coil U1, the coil V1, the coil W1, the coil U3, the coil V3, and the coil W3 are arranged in order from the left.

  Further, as shown in FIGS. 1 and 2, the coils U1, U2, U3 in the U phase are connected in series with the coil U1 disposed just in the center as an end, and there are other V phases and W phases. However, the coils V1 and W1 are connected in series in the same manner.

  Further, the end on the coil U1 side which is one end in the U phase is connected to the end on the coil V1 and W1 side which is one end in the V phase and the W phase, respectively, and the U phase, V phase and W phase are Y Connected.

  The other ends of the U-phase, V-phase, and W-phase are connected to the U-phase, V-phase, and W-phase coils U1, U2, U3, V1, V2, V3, W1, via power cables 8, 9, and 10, respectively. It is connected to a driver 11 that supplies current to W2 and W3.

  Further, the linear actuator 1 includes a position sensor 14 that is fixed to the small diameter portion 2 b of the outer tube 2 and detects the relative position of the rod 3 with respect to the outer tube 2. An electrical angle can be obtained, and a signal composed of a voltage output from the position sensor 14 is input to the driver 11.

  The driver 11 includes, for example, a power source, a PWM circuit, and a controller that controls the PWM circuit, although not shown in detail, and includes an electrical angle of the field 4 detected by the position sensor 14 and a host (not shown). On the basis of a control command input from the control device, the duty ratio and the energization timing are obtained, the energization phase is switched, and the coils U1, U2 of the U-phase, V-phase, and W-phase are controlled by PWM control. , U3, V1, V2, V3, W1, W2, and W3 can be controlled to control the thrust of the linear actuator 1 and the direction in which the thrust is generated. In controlling the linear actuator 1, it is only necessary to know the relative position of the permanent magnet 5 with respect to the core 6, and various known sensors can be used as the position sensor 14.

  Subsequently, the short-circuit means 7 includes a bypass 15 that connects between the U-phase coil U2 and the coil U1, and between the V-phase coil V2 and the coil V1, and between the V-phase coil V2 and the coil V1. , A relay 16 that connects the W-phase coil W2 and the coil W1, a relay 17 as a first switch provided in the middle of the bypass 15, and a second switch provided in the middle of the bypass 16 The relay 18 is provided. Since the first switch and the second switch only need to be able to close the bypasses 15 and 16, switches other than the relays 17 and 18 may be employed.

  When the current supply from the driver 11 is cut off, the relay 17 closes and opens the bypass 15 to connect the U phase and the V phase. When the current supply from the driver 11 is cut off, the relay 18 closes and opens the bypass 16 to connect the U phase and the W phase.

  Therefore, when the current supply from the driver 11 is cut off, the short-circuit means 7 closes the coils U1, V1, W1 installed in a predetermined specific axial range L and connects them in parallel. Form a circuit. Thus, the short circuit means 7 short-circuits only the coils U1, V1, and W1. The coils U1, V1, and W1 may be connected in series.

  Further, the specific axial range L can be arbitrarily set, and in this embodiment, the left end of the coil U1 installed at the central portion of the core 6 is set to the right end of the coil W1. The coils U1, V1, and W1 installed in are short-circuited.

  In addition to the power supply to the driver 11 being cut off, for example, the driver 11 has some control failure, such as disconnection of a cable that supplies current to each phase of U, V, and W, or the occurrence of control failure. When a failure occurs, the power to the relays 17 and 18 is cut off, the coils U1, V1 and W1 are short-circuited, and normal operation of the linear actuator 1 cannot be expected. Therefore, the current supply to the coil group C is cut off. It is like that.

  Thus, when the coils U1, V1, W1 are short-circuited by the short-circuit means 7 and the current to the coil group C including the coils U1, V1, W1 is cut off, the outer tube 2 and the rod 3 move relative to each other. At this time, only when the field 4 provided on the rod 3 passes through the central part of the core 6 where the coils U1, V1, W1 in which the short-circuited coils U1, V1, W1 are installed, currents due to the induced electromotive force flow through the coils U1, V1, W1. Even if the electromagnetic force is generated to suppress the movement of the magnetic field 4 and the field 4 moves while facing the opposite ends of the core 6 on which the other coils U2, V2, W2, U3, V3, W3 are installed. Since U2, V2, W2, U3, V3, and W3 are not short-circuited and are not closed circuits, no current flows and no electromagnetic force is generated.

  Therefore, when the field 4 passes through the central portion of the core 6, the movement is hindered by the electromagnetic force, and the rod 3 is positioned at the center of the stroke with respect to the outer tube 2. Further, even if the rod 3 strokes toward both ends of the stroke range with respect to the outer tube 2, when the expansion and contraction direction is reversed and the stroke returns to the center of the stroke, braking by electromagnetic force is applied and the rod 3 is difficult to move with respect to the outer tube 2. Thus, the rod 3 is positioned at the center of the stroke with respect to the outer tube 2.

  That is, when the field 4 is within a predetermined axial range within the axial installation range of the coil group C, the rod 3 is braked against the outer tube 2, and there is a problem at the time of failure. However, the rod 3 can be positioned at a specific position with respect to the outer tube 2, the movement of the rod 3 with respect to the outer tube 2 can be suppressed, and the rod 3 can be held at the specific position with respect to the outer tube 2.

  Further, as described above, even if the rod 3 deviates from the specific position with respect to the outer tube 2, the braking force does not work at any position other than the specific position and freely expands and contracts. When it is returned, it can be braked and repositioned, so return to a specific position is not hindered. Therefore, even if a failure occurs, the displacement of the linear actuator 1 can be quickly moved to a specific position. This linear actuator 1 can be used to return the displacement to a specific position and retain it as it is when the failure occurs. For example, it is most suitable for driving moving blades such as aircraft ladders, ailerons, elevators and flaps.

  Furthermore, in this embodiment, one end of the coils U1, V1, W1 installed in a specific axial range is Y-connected, so that the number of bypasses required for short-circuiting is two bypasses 15, 16. In addition, the number of switches is only two, that is, the relay 17 that is the first switch and the relay 18 that is the second switch, and the wiring length of the bypasses 15 and 16 can be shortened. Contributes to cost reduction. Although it is possible to Δ-connect the U-phase, V-phase, and W-phase, the above-described advantages can be obtained by Y-connecting.

  Further, in the above description, the short-circuit means 7 is configured to short-circuit the coils U1, V1, W1 in one closed circuit, but it is also possible to short-circuit each of the coils U1, V1, W1 independently. it can.

  Further, a resistor may be provided on one or the other of the bypasses 15 and 16 to increase the braking force when the short-circuit means 7 short-circuits the coils U1, V1, and W1. Since the linear actuator 1 converts the kinetic energy of the rod 3 and the outer tube 2 into electric energy by the field 4 and the coils U1, V1, and W1, the electric energy is converted into heat by the resistance and consumed. Thus, the braking force can be increased. Thus, the holding force for holding the rod 3 at a specific position with respect to the outer tube 2 can be increased by increasing the braking force. In addition, since resistance functions only at the time of a short circuit, when the linear actuator 1 is functioning normally, an energy loss does not arise.

  Furthermore, as described above, the specific range in the axial direction is a range in which the coils U1, V1, and W1 installed in the central portion of the core 6 are installed. When it is desired to suppress the relative displacement of the outer tube 2 of the rod 3 at the time of the most contraction, that is, the displacement of the linear actuator 1, for example, the coils U2, V2, and W2 disposed at both ends of the core 6 are short-circuited. Apart from this, the coils U3, V3, W3 may be short-circuited. Further, instead of short-circuiting the three-phase coils, only the U-phase coil and the V-phase coil may be short-circuited, and the displacement of the linear actuator 1 at the time of maximum expansion and contraction is suppressed. For example, the two coils U2 and V2 at the left end of the core 6 may be short-circuited, and the two coils V3 and W3 at the right end of the core 6 may be short-circuited.

  In this embodiment, the coil group C is constituted by three-phase coils U1, U2, U3, V1, V2, V3, W1, W2, and W3 of U, V, and W. However, the present invention is not limited to this. For example, it may be two-phase or four or more phases.

  Furthermore, although the number of coils of each phase is three in the above place, it is not limited to this.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

The present invention can be used for a linear actuator.

DESCRIPTION OF SYMBOLS 1 Linear actuator 2 Outer tube 2a Bottom part 2b Small diameter part 3 Rod 3a Rod part 3b Guide part 3c Slide ring 3d Mounting part 4 Field 5 Permanent magnet 6 Core 6a Slot 6b Polar tooth 7 Short-circuit means 8, 9, 10 Power cable 11 Driver 12 Slide bearing 13 Mounting portion 14 Position sensor 15, 16 Bypass 17 Relay as first switch 18 Relay as second switch C Coil group coils U1, U2, U3, V1, V2, V3, W1, W2, W3

Claims (5)

An outer tube, a rod that is movably inserted into the outer tube, a field that includes a plurality of permanent magnets and is held by one of the outer tube and the rod, and the other of the outer tube and the rod that faces the field In a linear actuator that generates a thrust that relatively displaces the outer tube and the rod in the axial direction, the axial range in which the coil group is installed is the axial length of the field. A linear actuator comprising a short-circuit means for short-circuiting a coil installed in a specific axial range when a failure occurs. 2. The linear actuator according to claim 1, wherein the short-circuit means connects and short-circuits the coils installed in a specific axial range so as to form a closed circuit. 3. The linear actuator according to claim 1, wherein when the specific axial direction range is a plurality of ranges that are not continuous in the axial direction, the short-circuit means shorts the coil for each of the plurality of ranges. The coil group is provided with three phases formed by connecting a plurality of coils in series, and each phase coil is arranged so as to appear in the axial direction in order, and the three-phase coil is Y-connected within a specific axial range. The short-circuit means includes a first switch that connects any two phases of the three phases at the time of failure, one phase that is not connected by the first switch at the time of failure, and any one of the other two phases. A linear actuator according to any one of claims 1 to 3, further comprising a second switch for connecting the two. The linear actuator according to claim 1, wherein the short-circuit unit short-circuits the coil through a resistor.

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