JP2023142751A - Cylindrical linear motor - Google Patents

Abstract

To provide a cylindrical linear motor that can obtain a cushioning effect near the end of the stroke toward the contraction side.SOLUTION: A cylindrical linear motor 1 includes: a cylindrical field 6 having a plurality of annular permanent magnets 10a, 10b stacked such that north poles and south poles are arranged alternately on the inner circumference in the axial direction; an armature 2 that is inserted into the inner peripheral side of the field 6 so as to be freely movable in the axial direction; a cylindrical rod 11 having the armature 2 attached to its outer periphery and inserted into the field 6 so as to be movable in the axial direction; a guide rod 16 that can enter the rod 11; and a friction ring 50 attached to either the inner circumference of the rod 11 or the outer circumference of the guide rod 16. When the friction ring 50 is contracted to the vicinity of the contraction side stroke end, the friction ring comes into slide contact with the other of the inner circumference of the rod 11 or the outer circumference of the guide rod 16.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cylindrical linear motor.

A cylindrical linear motor includes, for example, a bottomed cylindrical outer cylinder, a plurality of permanent magnets fixed to the inner periphery of the outer cylinder so that S and N poles are arranged alternately in the axial direction, and A cylindrical mover with a standing mover side rod, a cylindrical stator side rod and an armature attached to the outer periphery of the stator side rod, and can be moved in the axial direction within the mover. Some types include a stator that is inserted into the

In a cylindrical linear motor configured in this way, the mover side rod is inserted into the stator side rod via a bearing, and the movement of the mover in the axial direction with respect to the stator is controlled by the movement of the stator side rod. It is guided by a child side rod (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2013-29159

In such a cylindrical linear motor, the sliding resistance between the bearing and the mover side rod is constant, and even if the motor contracts close to the stroke end on the contraction side, it has a cushioning effect that suppresses movement toward the stroke end. There is a problem in that it is not possible to reduce the impact when the vehicle bottoms out.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cylindrical linear motor that provides a cushioning effect near the end of the stroke toward the contraction side.

In order to achieve the above object, the cylindrical linear motor of the present invention has a cylindrical field having a plurality of annular permanent magnets stacked so that N poles and S poles are alternately arranged in the axial direction. an armature that is inserted into the inner circumference of the field so as to be movable in the axial direction; It includes a rod, a guide rod that can enter into the rod, and a friction ring attached to the outer periphery of the guide rod, and when contracted to the vicinity of the contraction side stroke end, the friction ring comes into sliding contact with the inner periphery of the rod.

According to the cylindrical linear motor configured in this manner, when the friction ring enters the rod and comes into sliding contact with the rod, a frictional force is generated, thereby providing a cushioning effect that prevents contraction of the cylindrical linear motor.

Further, in the cylindrical linear motor, the guide rod has a guide part that can be inserted into the rod, a base end part provided at the base end of the guide part, and an elastic ring attached to the outer periphery of the base end part. The barrel has a cylindrical shape and holds a field, and it has a cylindrical shape with a bottom and is provided at the terminal end of the barrel and has a hole at the bottom, into which an elastic ring is fitted together with the base end. It may also include a bottom cap and a plate attached to the bottom cap and suspending the guide rod.

According to the cylindrical linear motor configured in this way, the guide rod fits into the hole of the bottom cap via the elastic ring and is suspended by the plate, so that the guide rod is pushed into the bottom cap by the deformation of the elastic ring. Eccentricity in the radial direction and inclination of the guide rod with respect to the bottom cap are allowed. According to the cylindrical linear motor configured in this way, it is possible to prevent the sliding resistance between the rod and the rod guide from increasing, thereby ensuring smooth expansion and contraction operation of the cylindrical linear motor. The assembly work of inserting the rod guide into the shaft is also facilitated.

According to the cylindrical linear motor of the present invention, a cushioning effect can be exerted near the end of the stroke toward the contraction side.

FIG. 2 is a longitudinal cross-sectional view of a cylindrical linear motor in one embodiment. It is a bottom view of the cylindrical linear motor in one embodiment.

The present invention will be described below based on the embodiments shown in the figures. As shown in FIG. 1, a cylindrical linear motor 1 in one embodiment includes a plurality of annular permanent magnets 10a and 10b stacked such that north poles and south poles are alternately arranged in the axial direction. A cylindrical field 6, an armature 2 inserted into the inner periphery of the field 6 so as to be movable in the axial direction, and a cylindrical armature 2 with the armature 2 attached to the outer periphery and an axial shaft inserted into the field 6. It is configured to include a rod 11 that is inserted so as to be movable in a direction, a guide rod 16 that can enter into the rod 11, and a friction ring 50 that is attached to the outer periphery of the guide rod 16.

Each part of the cylindrical linear motor 1 will be described in detail below. The armature 2 includes a core 3 and a winding 5. The core 3 includes a cylindrical core body 3a and a plurality of annular teeth 3b provided at intervals in the axial direction on the outer circumference of the core body 3a.

The core 3 is cylindrical as described above, and as shown in FIG. A slot 4 is formed between them, which is an air gap into which a winding 5 is attached. Further, in this embodiment, a total of nine slots 4 are provided between adjacent teeth 3b, 3b in FIG. A winding 5 is wound and attached to this slot 4. The winding 5 is composed of three-phase windings: a U-phase winding, a V-phase winding, and a W-phase winding. The nine slots 4 have, in order from the left in FIG. 1, W phase, W phase, W phase and V phase, V phase, V phase, V phase and U phase, U phase, U phase, U phase and W phase is installed.

The armature 2 is attached to the outer periphery of the tip of a cylindrical rod 11 made of a non-magnetic material, which is an output shaft. The rod 11 includes a cylindrical first rod 20 and a cylindrical second rod 21 having a core 3 attached to its outer periphery and screwed onto the inner periphery of the first rod 20 .

The first rod 20 has a rod body 22 that is cylindrical and has threaded portions 22a and 22b on the outer periphery at the left end in FIG. 1 and the inner periphery at the right end in FIG. 1, respectively, and a bracket 23a for attaching the cylindrical linear motor 1 to the device. The rod cap 23 is screwed onto a threaded portion 22a at the left end of the rod body 22 in FIG. 1 to close the left end of the rod body 22.

Further, an annular slider 25 is fitted onto the outer periphery of the right end of the rod body 22 in FIG. The slider 25 has a sliding contact portion 25a that slides on the inner periphery of a cylindrical portion 9b, which will be described later, and a sliding contact portion with an outer diameter provided on the proximal end side of the rod 11, which is the left side of the sliding contact portion 25a in FIG. 25a, an annular groove 25c provided along the circumferential direction on the outer periphery of the small diameter portion 25b, and a flange 25d provided on the inner periphery of the right end in FIG. A rubber seal ring 26 as an elastic body is attached to the annular groove 25c of the slider 25. Furthermore, the inner diameter of the flange 25d is greater than or equal to the inner diameter of the rod body 22 and less than or equal to the outer diameter of the rod body 22. When the slider 25 is fitted to the rod body 22, the flange 25d is positioned at the right end of the rod body 22 in FIG. come into contact with the surface.

The second rod 21 includes a cylindrical core holding cylinder 21a on the outer periphery of which the core 3 is attached, and an annular slider 21b provided on the outer periphery of the right end of the core holding cylinder 21a in FIG. Further, a threaded portion 21c is provided on the outer periphery of the base end, which is the left end in FIG. A large diameter portion 21d is provided. Then, when the base end of the core holding cylinder 21a is inserted into the inner periphery of the rod body 22 of the first rod 20 at the right end in FIG. The rod 21 is connected. Thus, in this embodiment, the rod 11 is composed of the first rod 20 and the second rod 21 and has a cylindrical shape.

Further, the core 3 is fitted and attached to the outer periphery of the core holding cylinder 21a of the second rod 21. Since the outer diameter of the core holding cylinder 21a is smaller than the outer diameter of the rod body 22 in the first rod 20, the second rod 21 on which the armature 2 is attached is attached to the first rod 20 on which the slider 25 is attached. When connected in the manner described above, the armature 2 and the slider 25 are sandwiched and fixed between the right end of the first rod 20 in FIG. 1 and the slider 21b of the second rod 21. When the armature 2 is attached to the rod 11 in this manner, the core 3 is fixed to the rod 11 while being sandwiched between the slider 21b and the slider 25. Note that in this embodiment, the armature 2 is configured to have only a single core 3, but may be configured to have a plurality of cores 3 in order to improve thrust or the like.

Next, the rod 11 is provided with a cover 17 that covers the outer periphery of the rod 11 to form a gap G. Specifically, the cover 17 has a cylindrical shape, and one end is fitted to the outer periphery of an annular cover end 18 provided on the outer periphery of the rod 11, and the other end is fitted to the outer periphery of the small diameter portion 25b of the slider 25. and is attached to the rod 11.

Lead wires L are housed in the gap G between the cover 17 and the rod 11, and connect the windings 5 of each phase attached to the core 3 to an external drive circuit (not shown). Wiring between the windings 5 and the lead wires L can be carried out in this state, which facilitates the assembly of the cylindrical linear motor 1.

Continuing, in this embodiment, the field 6 is configured to include permanent magnets 10a that are alternately stacked in the axial direction and serve as a plurality of annular main magnetic poles, and permanent magnets 10b that serve as a plurality of annular sub-magnetic poles. ing. Further, the field 6 is connected to a back yoke 8 formed of a cylindrical magnetic material attached to the outer periphery, and a cylindrical barrel 7 and a cylindrical inner tube 9 inserted into the barrel 7. It is housed within an annular gap.

The barrel 7 is made of a non-magnetic material, and has a threaded portion 7a provided on the inner periphery of the open end on the left side in FIG. 1, and a threaded portion 7b provided on the outer periphery of the open end on the right side in FIG. We are prepared. A bottom cap 12 is screwed onto the outer periphery of the open end of the barrel 7 on the right side in FIG. 1, and the open end on the right side in FIG. 1 of the barrel 7 is closed. The bottom cap 12 has a bottomed cylindrical shape including an annular bottom portion 12a having a hole 12a1 in the center and a cylindrical portion 12b. It is attached to the right end in Figure 1. Further, the bottom cap 12 includes a bracket that projects from the bottom portion 12a in the axial direction and is formed by a pair of mounting pieces 12c, 12c facing each other. The bracket is used to attach the cylindrical linear motor 1 to equipment (not shown).

Further, the bottom cap 12 has a bottom portion 12a facing the right end 6b in FIG. 1, which is the other end of the field 6. Furthermore, as shown in FIG. 2, a plate 13 is attached to the bottom part 12a of the bottom cap 12, which is arranged parallel to the mounting pieces 12c and 12c and crosses the hole 12a1 of the bottom part 12a when the bottom cap 12 is viewed from the axial direction. ing. The plate 13 has a through hole 13a in the center, and is fixed to the bottom 12a by bolts 14, which are screwed between the mounting pieces 12c, 12c and across the through hole 13a. Therefore, the through hole 13a in the center of the plate 13 is arranged coaxially with the hole 12a1 in the bottom portion 12a of the bottom cap 12 when viewed from the axial direction.

Next, the inner tube 9 is made of a non-magnetic material, and has an annular head portion 9a that is attached to the open end of the barrel 7 at the left end in FIG. The cylinder part 9b extends from the inner periphery of the right end in FIG. 1 of the head part 9a and is inserted into the inner periphery of the field 6. Therefore, the right end in FIG. 1 of the head portion 9a of the inner tube 9 functions as a head member that faces the left end 6a in FIG. 1, which is one end of the field 6 attached to the outer periphery of the cylinder portion 9b.

In addition, the inner tube 9 is provided with a curved surface 9c at the boundary between the right end of the head portion 9a in FIG. 1 and the cylindrical portion 9b. This prevents stress from concentrating at the boundary. Note that in order to avoid stress concentration in this manner, a tapered surface may be provided at the boundary between the head portion 9a and the cylindrical portion 9b.

The field magnet 6 includes a plurality of permanent magnets 10a serving as a plurality of annular main magnetic poles and a plurality of permanent magnets 10b serving as a plurality of annular sub-magnetic poles, which are alternately stacked and inserted in the axial direction on the inner circumference of a cylindrical back yoke 8. It is configured with. The permanent magnet 10a and the permanent magnet 10b are laminated with an adhesive interposed therebetween to prevent scattering. In FIG. 1, the triangular marks written on the main pole permanent magnet 10a and the sub pole permanent magnet 10b indicate the direction of magnetization, and the magnetization direction of the main pole permanent magnet 10a is in the radial direction. The direction of magnetization of the permanent magnet 10b of the sub-pole is the axial direction. The permanent magnet 10a as the main pole and the permanent magnet 10b as the sub-pole are arranged in a Halbach arrangement, and on the inner peripheral side of the field 6, they are arranged so that S poles and N poles appear alternately in the axial direction. .

Furthermore, in the cylindrical linear motor 1 of the present embodiment, the axial length of the main pole permanent magnet 10a is longer than the axial length of the sub pole permanent magnet 10b. In this way, by increasing the axial length of the main pole permanent magnet 10a, the magnetic resistance between the main pole permanent magnet 10a and the core 3 can be reduced, and the magnetic field acting on the core 3 can be increased. The thrust of the cylindrical linear motor 1 can be improved.

Further, in the cylindrical linear motor 1 of this embodiment, a back yoke 8 is provided on the outer periphery of the permanent magnets 10a and 10b. By providing the back yoke 8, a magnetic path with low magnetic resistance can be ensured, thereby suppressing an increase in magnetic resistance due to a shortening of the axial length of the permanent magnet 10b of the sub-pole. Therefore, if the axial length of the main pole permanent magnet 10a is made longer than the axial length of the sub pole permanent magnet 10b, and a cylindrical back yoke 8 is provided around the outer periphery of the permanent magnets 10a, 10b, a cylindrical linear motor can be obtained. 1 thrust can be greatly improved. The thickness of the back yoke 8 may be set to a thickness suitable for suppressing an increase in external magnetic resistance of the permanent magnet 10a of the main pole.

Further, the armature 2 is inserted into the inner peripheral side of the field 6 so as to be freely movable in the axial direction, and the field 6 applies a magnetic field to the core 3 . Note that since the field 6 only needs to apply a magnetic field to the movable range of the core 3, the installation range of the permanent magnets 10a and 10b may be determined according to the movable range of the core 3. Therefore, it is not necessary to install the permanent magnets 10a and 10b in the annular gap between the barrel 7 and the cylindrical portion 9b in a range where the core 3 cannot be opposed.

In the present embodiment, the field 6 is composed of permanent magnets 10a and 10b in a Halbach arrangement, but a ring-shaped permanent magnet that is magnetized in the radial direction and has an N pole on its inner circumference and It may also be constructed by sequentially stacking a ring-shaped permanent magnet that is magnetized and has an S pole on its inner periphery.

An annular head-side spacer 40, a field 6, and an annular end-side spacer 41 are housed between the outer periphery of the cylindrical portion 9b and the inner periphery of the barrel 7. The head side spacer 40 has a cylindrical shape, and has a shape in which the outer diameter on the opposite field side, which is the left side in FIG. 1, is larger than the outer diameter on the field side, which is the right side in FIG. The left end of the head spacer 40 in FIG. 1 contacts the right end surface of the head portion 9a of the inner tube 9 in FIG. 1, and the right end of the head spacer 40 in FIG. The right end of the head-side spacer 40 in FIG. 1 enters the gap between the cylindrical portion 9b and the back yoke 8, and directly faces and abuts the left end 6a of the field 6.

The end spacer 41 has a cylindrical shape, and has a shape in which the outer diameter on the opposite field side, which is the right side in FIG. 1, is larger than the outer diameter on the field side, which is the left side in FIG. The right end of the end spacer 41 in FIG. 1 is in contact with the left end surface of the bottom 12a of the bottom cap 12 in FIG. 1, and the left end of the end spacer 41 in FIG. 1 is in contact with the right end 6b of the field 6. The left end of the end spacer 41 in FIG. 1 enters a gap between the cylindrical portion 9b and the back yoke 8, and directly faces and abuts the right end 6b of the field 6.

Then, an annular head-side spacer 40, a field 6, and an annular end-side spacer 41 are fitted into the outer periphery of the cylindrical portion 9b in order from the left in FIG. After tightening, when the bottom cap 12 is attached to the right end of the barrel 7 in FIG. The field 6 is fixed to the inner periphery of the barrel 7. Note that the back yoke 8 attached to the outer periphery of the field magnet 6 is not held between the head portion 9a and the bottom cap 12 in the axial direction, but is bonded to the field magnet 6 and therefore does not move within the barrel 7. If the movement of the back yoke 8 in the axial direction with respect to the field 6 can be restrained by the magnetic force of the field 6, the back yoke 8 does not need to be bonded to the field 6.

An annular seal member 28 is provided on the inner periphery of the head portion 9a and is in sliding contact with the outer periphery of the cover 17 that covers the outer periphery of the first rod 20. Dust, water, etc. are prevented from entering the motor 1.

A rod 11 to which the armature 2 is attached is inserted into the inner tube 9 so as to be movable in the axial direction, and sliders 21b and 25 are in sliding contact with the inner periphery of the cylindrical portion 9b to move the armature 2 in the axial direction. Movement will be guided.

The cylindrical portion 9b forms a gap between the outer periphery of the core 3 and the inner periphery of each permanent magnet 10a, 10b, and also plays the role of guiding the axial movement of the core 3 in cooperation with the sliders 21b, 25. There is. Note that in this embodiment, the armature 2 is configured to have only a single core 3; however, if it has a plurality of cores 3, the cores 3, A slider that slides into contact with the inner periphery of the cylindrical portion 9b may also be provided between the cylindrical portions 9b and 9b.

Further, a guide rod 16 is inserted into the hole 12a1 of the bottom portion 12a of the bottom cap 12. The guide rod 16 includes a cylindrical guide portion 16a that can be inserted into the rod 11, and a cylindrical guide portion 16a that is provided at the right end in FIG. It includes a cylindrical base end 16b and an elastic ring 16c attached to the outer periphery of the base end 16b, and is attached to the bottom 12a of the bottom cap 12 via the plate 13.

Specifically, a screw hole is formed at the right end of the guide portion 16a, and the guide rod 16 is attached to the plate by a bolt 19 inserted into a through hole 13a of the plate 13 fixed by the bolts 14, 14 of the bottom portion 12a. 13. In this way, the guide rod 16 is inserted into the rod 11 with one end suspended by the plate 13. The outer diameter of the base end portion 16b is smaller than the inner diameter of the hole 12a1 in the bottom portion 12a of the bottom cap 12. The inner diameter of the through hole 13a in the plate 13 is larger than the outer diameter of the shaft of the bolt 19, and the outer circumference of the base end 16b of the guide rod 16 is fitted into the hole 12a1 of the bottom cap 12. A matching elastic ring 16c is attached. In the cylindrical linear motor 1 of this embodiment, the elastic ring 16c is an O-ring, and the outer diameter of the elastic ring 16c is larger than the inner diameter of the hole 12a1.

When the base end 16b of the guide rod 16 is inserted into the hole 12a1 of the bottom cap 12, a gap is created between the outer periphery of the base end 16b and the inner periphery of the bottom 12a of the bottom cap 12, causing the elastic ring 16c to contract in diameter. and tightly adheres to the inner periphery of the bottom portion 12a. Therefore, the guide rod 16 is elastically supported by the elastic ring 16c while being inserted into the hole 12a1 of the bottom cap 12, so that eccentricity and inclination in the radial direction with respect to the bottom cap 12 are allowed.

The right end side of the guide rod 16 in FIG. 1 is connected to the plate 13 by a bolt 19 inserted into the through hole 13a of the plate 13. In this way, the guide rod 16 is not supported at its left end in FIG. 1, but only at its right end in FIG. . Further, the plate 13 has elasticity and is allowed to twist and bend. Therefore, the guide rod 16 is suspended by the plate 13 and elastically supported by the bottom cap 12 by the elastic ring 16c, so that even if it is connected to the bottom cap 12 via the plate 13, the guide rod 16 does not move in the radial direction with respect to the bottom cap 12. A slight eccentricity to the bottom cap 12 and a slight inclination of the guide rod 16 with respect to the bottom cap 12 are allowed.

The guide portion 16a of the guide rod 16 is always in sliding contact with the inner circumference of the rod 11 even when the cylindrical linear motor 1 expands or contracts, and guides the movement of the armature 2 in the axial direction with respect to the field 6. . More specifically, the guide portion 16a of the guide rod 16 is slidably inserted toward the distal end side of the large inner diameter portion 21d of the second rod 21.

In this way, in the cylindrical linear motor 1 according to the present embodiment, the guide rod 16 is in sliding contact with the inner circumference of the rod 11, and the sliders 21b and 25 are in sliding contact with the inner tube 9. It can move smoothly in the axial direction without being eccentric with respect to the field 6.

Furthermore, in the cylindrical linear motor 1 configured in this manner, the inner tube 9 that guides the axial movement of the armature 2 and prevents the armature 2 from eccentricity with respect to the field 6 is integrally constructed with the head cap. Therefore, the inner tube 9 and the head cap are less likely to be distorted, and the sliders 21b and 25 can smoothly slide on the inner periphery of the inner tube 9, allowing for smooth expansion and contraction.

In the cylindrical linear motor 1, when the slider 21b comes into contact with the bottom of the bottom cap 12 during the contraction operation in which the armature 2 moves to the right in FIG. That is, in the cylindrical linear motor 1 of this embodiment, the position where the slider 21b abuts the bottom portion 12a of the bottom cap 12 is the stroke end on the contraction side. An annular groove 16a1 is provided on the outer periphery of the guide portion 16a of the guide rod 16 near the base end 16b, and a friction ring 50 made of an O-ring is installed in the annular groove 16a1. ing. Specifically, the friction ring 50 is disposed on the outer periphery of the guide portion 16a at a position where it is inserted into the rod 11 before the cylindrical linear motor 1 is most contracted. Therefore, the friction ring 50 allows the cylindrical linear motor 1 to contract to the vicinity of the contraction side stroke end during the contraction operation in which the armature 2 of the cylindrical linear motor 1 moves to the right in FIG. 1 relative to the field 6. Then, it is inserted into the rod 11. The outer diameter of the friction ring 50 installed in the annular groove 16a1 is set to be larger than the inner diameter on the right end side of the second rod 21, so that when the friction ring 50 is inserted into the second rod 21, friction is generated. Frictional force is generated between the ring 50 and the inner circumference of the second rod 21. The frictional force acts as a resistance that suppresses further displacement of the rod 11 toward the contraction side with respect to the guide rod 16. Therefore, when the cylindrical linear motor 1 of this embodiment contracts to the vicinity of the stroke end on the contraction side, the friction The frictional force generated by the ring 50 provides a cushioning effect that prevents contraction of the cylindrical linear motor 1.

Note that the cylindrical linear motor 1 of this embodiment accommodates a stroke sensor S within the rod 11. In this embodiment, the stroke sensor S is a linear variable differential transformer, and although not shown in detail, it includes a cylindrical sensor body 30 housing a primary coil and two secondary coils, and a sensor body 30. It is configured to include a probe 31 which is inserted movably in the axial direction and is an element to be detected. Note that the linear variable differential transformer detects the position of the probe 31 from the difference in voltage induced between the two secondary coils when an alternating current voltage is applied to the primary coil.

The sensor main body 30 is fixed within the first rod 20 to which the armature 2 is not mounted on the outer periphery, and is accommodated in a range where it does not face the armature 2 in the radial direction of the rod 11. Further, the probe 31 in the stroke sensor S is rod-shaped and is attached to the tip of the guide portion 16a of the guide rod 16 via a sensor holding rod 32. Therefore, it is connected to the field 6 via the probe 31 as an element to be detected, the guide rod 16, and the barrel 7. The probe 31 is inserted into the sensor body 30 as described above. Therefore, as the armature 2 moves in the axial direction with respect to the field 6, the probe 31 moves relative to the sensor body 30 in the axial direction and moves within the sensor body 30.

Since the guide rod 16 that holds the probe 31 is slidably inserted into the rod 11 that accommodates the sensor body 30, eccentricity of the probe 31 in the radial direction with respect to the sensor body 30 is prevented. Although not shown, the wiring for energizing the primary coil of the sensor body 30 and the wiring connected to the secondary coil are pulled out through a hole provided in the rod cap 23 and connected to a controller (not shown).

A controller (not shown) detects the position of the rod 11 with respect to the field 6 with a stroke sensor S, grasps the electrical angle of the core 3 with respect to the field 6, switches the energization phase, and uses PWM control to control each winding 5. The thrust in the cylindrical linear motor 1 and the moving direction of the armature 2 are controlled by controlling the amount of current. Note that the control method in the controller described above is an example and is not limited to this. Further, when an external force that causes a relative displacement between the armature 2 and the field 6 in the axial direction acts, a thrust is generated to suppress the relative displacement by energizing the winding 5 or by an induced electromotive force generated in the winding 5. can be generated to cause the cylindrical linear motor 1 to damp the vibrations and motion of the equipment caused by the external force, and it is also possible to regenerate energy to generate electric power from the external force.

As described above, the cylindrical linear motor 1 of the present invention has a cylindrical field having a plurality of annular permanent magnets 10a and 10b stacked so that N poles and S poles are alternately arranged in the axial direction. A magnet 6, an armature 2 that is inserted into the inner circumference of the field 6 so as to be able to move in the axial direction, and an armature 2 that is cylindrical and has the armature 2 attached to the outer circumference and is movable in the axial direction within the field 6. It includes a cylindrical rod 11 to be inserted, a guide rod 16 that can enter into the rod 11, and a friction ring 50 attached to the outer periphery of the guide rod 16. When contracted to near the contraction side stroke end, the friction ring 50 is in sliding contact with the inner periphery of the rod 11.

According to the cylindrical linear motor 1 configured in this way, when the friction ring 50 enters into the rod 11 and comes into sliding contact with the rod 11, a frictional force is generated, thereby providing a cushioning effect that prevents contraction of the cylindrical linear motor 1. . Further, according to the cylindrical linear motor 1 of the present embodiment, a cushion effect is obtained near the end of the stroke toward the contraction side, so the stroke speed of the cylindrical linear motor 1 toward the contraction side is reduced by the cushion effect. It can reduce the impact caused by bottoming out.

The stroke range in which the cushioning effect is generated can be tuned by adjusting the axial position of the friction ring 50 with respect to the guide portion 16a, and if you want to obtain a larger cushioning effect, as shown by the broken line, the stroke range of the friction ring 50 can be tuned. In addition, one or more friction rings 51 may be additionally provided at a position shifted in the axial direction of the guide portion 16a with respect to the friction ring 50.

Further, the friction ring 50 may be mounted on the inner circumference of the rod 11 at a position where the guide portion 16a is inserted when the cylindrical linear motor 1 exhibits a contraction operation up to the vicinity of the stroke end on the contraction side. . Even if the friction ring 50 is provided on the inner periphery of the rod 11 in this way, it slides into contact with the outer periphery of the guide portion 16a of the guide rod 16 before the cylindrical linear motor 1 is fully contracted, generates a frictional force, and provides a cushioning effect. Obtainable.

Furthermore, in the cylindrical linear motor 1 of the present embodiment, the guide rod 16 includes a guide portion 16a that can be inserted into the rod 11, a base end portion 16b provided at the base end of the guide portion 16a, and a base end portion 16a. The barrel 7 has a cylindrical shape and holds the field magnet 6, and has an elastic ring 16c attached to the outer periphery of the barrel 16b.The barrel 7 has a cylindrical shape with a bottom and is provided at the end of the barrel 7 and has a hole 12a1 in the bottom 12a. The bottom cap 12 has a base end portion 16b and an elastic ring 16c fitted into the hole 12a1, and a plate 13 that is attached to the bottom cap 12 and suspends the guide rod 16.

According to the cylindrical linear motor 1 configured in this way, the guide rod 16 fits into the hole 12a1 of the bottom cap 12 via the elastic ring 16c and is suspended by the plate 13, so that the guide rod 16 Eccentricity in the radial direction with respect to the bottom cap 12 and inclination of the guide rod 16 with respect to the bottom cap 12 are allowed. Therefore, even if the rod 11 and the bottom cap 12 are misaligned or slightly tilted, the guide portion 16a of the guide rod 16 can be inserted into the rod 11 without any force, and the rod 11 and the guide rod 16 can be easily inserted. This can prevent the sliding resistance between the two ends from increasing. As described above, according to the cylindrical linear motor 1 of the present embodiment, it is possible to prevent the sliding resistance between the rod 11 and the guide rod 16 from increasing, so that the cylindrical linear motor 1 can smoothly extend and contract. In addition, the assembly work of inserting the guide rod 16 into the rod 11 becomes easier.

Note that if the inner diameter of the through hole 13a of the plate 13 is larger than the outer diameter of the shaft portion of the bolt 19, the allowable range of eccentricity of the guide rod 16 with respect to the bottom cap 12 will be large, so the relationship between the guide rod 16 and the plate 13 will be increased. The ease of assembling the connecting parts can be improved.

Further, when the elastic ring 16c can also function as a seal, such as an O-ring, the elastic ring 16c seals between the base end 16b of the guide rod 16 and the inner periphery of the bottom 12a of the bottom cap 12. This also prevents dust, water, etc. from entering the cylindrical linear motor 1. Furthermore, since eccentricity and inclination of the guide rod 16 with respect to the bottom cap 12 are allowed and the guide rod 16 can be aligned with the rod 11, the sensor body 30 held by the rod 11 and the probe held by the guide rod 16 31 can be aligned.

In the cylindrical linear motor 1 of the present embodiment, the friction ring 50 is an O-ring, but it is sufficient to generate frictional force when slidingly contacting the rod 11 or the guide rod 16. In addition to the O-ring, a ring made of rubber or synthetic resin may be used. Although the elastic ring 16c is an O-ring, it is also possible to use a ring other than an O-ring made of rubber or synthetic resin as long as it can elastically support the guide rod 16 and allow for eccentricity and inclination with respect to the bottom cap 12. may be taken as

Although the preferred embodiments of the present invention have been described in detail above, modifications, variations, and changes can be made without departing from the scope of the claims.

DESCRIPTION OF SYMBOLS 1... Cylindrical linear motor, 2... Armature, 6... Field, 7... Barrel, 10a, 10b... Permanent magnet, 11... Rod, 12... Bottom cap , 12a... Bottom, 12a1... Hole, 13... Plate, 16... Guide rod, 16a... Guide portion, 16b... Base end, 16c... Elastic ring, 50, 51...Friction ring

Claims (2)

a cylindrical field having a plurality of annular permanent magnets stacked so that north poles and south poles are arranged alternately in the axial direction;
a cylindrical armature that is movably inserted into the inner peripheral side of the field;
a cylindrical rod having the armature attached to its outer periphery and inserted into the field so as to be movable in the axial direction;
a guide rod that can enter into the rod;
a friction ring attached to either the inner periphery of the rod or the outer periphery of the guide rod;
The cylindrical linear motor is characterized in that when the friction ring is contracted to the vicinity of a contraction-side stroke end, the friction ring comes into sliding contact with the other of the inner periphery of the rod or the outer periphery of the guide rod. The guide rod has a guide part that can be inserted into the rod, a base end part provided at the base end of the guide part, and an elastic ring attached to the outer periphery of the base end part,
a barrel that is cylindrical and holds the field;
a bottom cap having a cylindrical shape with a bottom, provided at the terminal end of the barrel and having a hole at the bottom, into which the elastic ring is fitted together with the base end;
The cylindrical linear motor according to claim 1, further comprising a plate attached to the bottom cap and suspending the guide rod.