JP2009127742A - Linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motor using a feed screw for actualizing stable linear drive of a movable body having a long stroke. <P>SOLUTION: In the linear motor 1, the feed screw 6 is rotatably held at both ends by a case 2 and the inclination of the feed screw 6 is suppressed. The movable body 7 is mounted on the feed screw 6. The movable body 7 has a carriage 5 engaging with the feed screw 6 inside the case 2, three connection shafts 4 extending from the carriage 5 and passing through the case 2, and an output member 3 connected to the three connection shafts 4 outside the case 2. A motor 9 and the feed screw 6 are mechanistically connected to each other via a transmission mechanism 10 consisting of a belt mechanism. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a linear drive device for linearly driving a movable body.

As a linear drive device for linearly driving a valve body or the like, a configuration in which a feed screw (lead screw) is formed on the free end side of a rotating shaft of a motor and a feed screw is screwed into a female screw portion of a movable body. It has been proposed (see, for example, Patent Document 1).
JP 2006-234033 A

  However, in the linear drive device described in Patent Document 1, the base end side of the rotating shaft is supported by a bearing, but the distal end side where the feed screw is formed on the rotating shaft is a free end. If the feed screw is lengthened in order to increase the stroke, the feed screw (rotary shaft) tends to tilt, and the operation of the valve body is not stable.

  In view of the above problems, an object of the present invention is to provide a linear drive device that can stably drive a movable body even when the stroke of the movable body is long when the movable body is linearly driven by a feed screw. There is to do.

  In order to solve the above problems, a motor, a feed screw that rotates about an axis based on the rotational drive of the motor, a movable body that engages with the feed screw and is linearly driven based on the rotation of the feed screw And a follow-up blocking mechanism for blocking the surrounding of the movable body when the feed screw rotates, and the motor, the feed screw, and the follow-up blocking mechanism are housed inside A carriage that has a case, both ends of the feed screw are rotatably held by the case, and the movable body engages with the feed screw in the case and moves linearly on the feed screw; A connecting member extending from the carriage to the outside of the case through the second facing portion; and an output member connected to the connecting member on the outside of the case.

  In the present invention, a drive mechanism such as a motor, a feed screw, a carriage, and a follow-up prevention mechanism is housed in the case, and the output member outside the case is linearly driven via the connecting member, so that dust, dirt, water droplets, etc. Even if the linear drive device is used in an environment where the air scatters, the drive mechanism is not easily contaminated by these. Therefore, it is possible to prevent a problem from occurring in the drive mechanism. Moreover, dust generated by high-speed rotation of the motor is not scattered outside the case. Furthermore, when the movable body is linearly driven by the feed screw, both ends of the feed screw are rotatably held by the case. Therefore, when the feed screw is lengthened and the stroke of the movable body is set long, the carriage is fed by the feed screw. In any of the above positions, the lead screw does not tilt or shake. Therefore, the carriage and the output member can be stably operated. Furthermore, since both ends of the feed screw are rotatably held by the case, the feed screw can be lengthened, and the members disposed in the middle part of the feed screw in the length direction can be minimized, so Almost the entire screw length direction can be used as the carriage movement range, and the stroke of the movable body can be easily set longer.

  In this invention, the said connection member can be comprised by 3 or more shaft bodies, for example. If comprised in this way, since a carriage and an output member can be connected firmly, the inclination of an output member can be prevented and operation | movement of an output member can be stabilized.

  In this invention, it is preferable that the said connection member is three or more shaft bodies extended in parallel with the center axis line of the said feed screw in the position surrounding the said feed screw. If comprised in this way, since a carriage and an output member are each supported by at least 3 points | pieces, the inclination of an output member can be prevented reliably and operation | movement of an output member can be stabilized. In addition, since the torsional rigidity of the movable body with respect to the torsional force around the central axis of the feed screw can be increased, the displacement of the output member when the torsional force is applied to the movable body can be suppressed, and the movable body Can be prevented from being deformed or damaged.

  In this case, a portion of the case through which the connecting member penetrates is a through hole that forms a sliding portion with an outer periphery of the connecting member, and the inside and the outside of the case have a surface that forms the through hole. Except for being sealed, it is preferable. With this configuration, when dust, dirt, water droplets, or the like enter the case from the side through which the connecting member passes, it is possible to prevent the intruding dust from scattering outside the case. it can.

  In the present invention, a transmission mechanism that transmits the rotation of the rotation shaft of the motor to the feed screw is provided, and the transmission mechanism includes a drive pulley attached to the rotation shaft of the motor and a driven pulley attached to the feed screw. And a belt hung on the drive pulley and the driven pulley. When a belt mechanism is used as the transmission mechanism, it is possible to suppress the vibration on the motor side from being transmitted to the feed screw side, so that the vibration of the feed screw can be suppressed. Therefore, the operations of the carriage and the output member can be stabilized.

  In the present invention, it is preferable to include at least one of position detection means for detecting the position of the movable body and rotation detection means for detecting the rotation amount of the feed screw. If comprised in this way, the positional information on an output member can be acquired and the origin of an output member can be detected. Further, since the rotation speed of the feed screw can be calculated based on the position of the output member and the rotation amount of the feed screw, the rotation speed of the feed screw can be changed according to the position of the output member.

  In the linear drive device to which the present invention is applied, both ends of the feed screw are rotatably held by the case. Therefore, when the feed screw is lengthened and the stroke of the movable body is set to be long, the carriage is not positioned on the feed screw. Even if it is in the position, the feed screw will not tilt or shake. Therefore, the carriage and the output member can be stably operated. Furthermore, since both ends of the feed screw are rotatably held by the case, the feed screw can be lengthened, and the members disposed in the middle part of the feed screw in the length direction can be minimized, so Almost the entire screw length direction can be used as the carriage movement range, and the stroke of the movable body can be easily set longer.

  Hereinafter, an embodiment of a linear drive device to which the present invention is applied will be described with reference to the drawings.

(Overall configuration of linear drive device)
1A and 1B are a plan view of a main part of a drive mechanism of a linear drive device to which the present invention is applied, and a longitudinal sectional view of the linear drive device. FIG. 2 is an explanatory diagram showing a state in which the movable body has moved upward in the linear drive device shown in FIG. FIG. 3 is a perspective view showing a state in which the case is omitted from the linear drive device shown in FIG.

  1A, 1B, and 2, a linear drive device 1 to which the present invention is applied includes a motor 9 and a feed screw that rotates around an axis L (center axis) based on the rotational drive of the motor 9. 6 and a movable body 7 that is linearly driven based on the rotation of the feed screw 6.

  The movable body 7 is engaged with the feed screw 6 to move linearly on the feed screw 6, the three connecting shafts 4 extending upward from the carriage 5, and the distal ends of the three connecting shafts 4. And a connected disk-shaped output member 3.

  In this embodiment, the motor 9, the feed screw 6, the carriage 5 and the like are accommodated in the case 2, and only the output member 3 and the distal end side of the connecting shaft 4 (on the output member 3 side of the connecting shaft 4) Located outside. As will be described in detail later, both ends of the feed screw 6 are rotatably held with respect to opposing portions (upper surface portion and bottom surface portion) in the case 2. In addition, a rotation prevention shaft 80 is disposed inside the case 2 in parallel with the feed screw 6, and both ends of the rotation prevention shaft 80 are also held by opposing portions (upper surface portion and bottom surface portion) in the case 2. ing.

  As shown in FIG. 3, the carriage 5 has a substantially isosceles triangular planar shape, and a feed screw 6 is screwed into a screw hole 5a formed at a position near the bottom of the isosceles triangle. In this embodiment, the three connecting shafts 4 extend in parallel to the axis L of the feed screw 6 at a position corresponding to the apex of a triangle surrounding the feed screw 6 (screw hole 5a). In this embodiment, the screw hole 5a is formed at a position corresponding to the center of gravity of an equilateral triangle whose apex is the position where the connecting shaft 4 is arranged. Are arranged at positions rotated 120 degrees each.

  A guide hole 5b through which the rotation prevention shaft 80 is inserted is formed near the top of the carriage 5. When the feed screw 6 is rotated by the guide hole 5b and the rotation prevention shaft 80, a movable body (carriage) is formed. A companion block mechanism 8 for blocking the companion is configured. Accordingly, when the feed screw 6 rotates, the movable body 7 moves on the feed screw 6 in the axis L direction while being guided in the axis L direction by the rotation prevention shaft 80.

  As shown in FIGS. 1A, 1 </ b> B, 2, and 3, a motor 9 and a transmission mechanism 10 for rotating the feed screw 6 are accommodated in the case 2. Various motors such as a brushed DC motor, a brushless DC motor, and a stepping motor can be used for the motor 9. In this embodiment, since a large torque is required as the lead angle of the feed screw 6 is increased, a DC motor with a brush is used as the motor 9.

  The transmission mechanism 10 includes a drive pulley 10a attached to the rotating shaft 9a of the motor 9, a driven pulley 10b attached to the proximal end portion of the feed screw 6, and an endless belt spanned between the drive pulley 10a and the driven pulley 10b. 10 c, and the rotation of the rotating shaft 9 a of the motor 9 is transmitted to the feed screw 6 through the transmission mechanism 10. A timing belt is used as the belt 10c.

(Configuration of detection means)
On the base end side (lower end side) of the feed screw 6, four rectangular magnets 111 are fixed to the driven pulley 10 b at positions rotated by 90 degrees in the circumferential direction, while being fixed in the case 2. A rotation detection sensor 112 including a Hall IC including a Hall element and a signal processing IC is mounted on the substrate 113. The rotation speed (rotation amount) and rotation of the feed screw 6 are rotated by the magnet 111 and the rotation detection sensor 112. A rotation detection device 11 (rotation detection means) that detects a direction is configured. As the rotation detection device 11, rotation detection may be performed using another sensor such as a rotary encoder. Further, the position of the rotation detection sensor 112 may be any position as long as the rotation of the feed screw 6 can be detected. Alternatively, the magnet 111 may be mounted on the rotating shaft 9a of the motor 9 or the feed screw 6 itself, and the rotation speed and rotation direction of the feed screw 6 may be calculated based on the detected value and the reduction ratio of the transmission mechanism 10.

  A magnet 121 is mounted on the upper surface of the carriage 5, and a magnetic sensor 122 including a hall element is mounted on a substrate 123 fixed in the case 2. A position detection device 12 for detecting the position of the movable body 7 via the position of the carriage 5 is configured. Therefore, it is possible to detect whether or not the movable body 7 has reached the lowermost side. In addition, as the position detection apparatus 12, a contact-type sensor, a photo sensor, etc. can also be used. Further, it is also possible to detect that the movable body 7 has reached the lowermost end by detecting the load of the motor 9.

(Case structure)
In this embodiment, the case 2 includes a lower case 21 and an upper case 22. The upper case 22 has a shape in which an upper opening of a cylindrical body 22a that opens at both ends is closed by a plate 23, and a flange 22c is formed at the lower end of the cylindrical body 22a.

  A centered portion of the plate 23 is formed with a bottomed circular concave portion 23a that is recessed upward. The circular concave portion 23a rotatably supports the small diameter portion 6a formed at the upper end portion of the feed screw 6. A bearing is constructed. In the plate 23, three through holes 23d through which the connecting shaft 4 passes are formed around the circular recess 23a. Here, each of the three through holes 23 d constitutes a sliding portion with the outer peripheral surface of the connecting shaft 4. For this reason, the plate 23 is comprised with resin excellent in slidability. In the plate 23, a bearing member having excellent slidability and sealability may be provided at a portion through which the connecting shaft 4 passes.

  The lower case 21 is a bottomed cylindrical body having an outer diameter slightly larger than that of the upper case 22, and a concave portion 21f that is recessed downward is formed at the bottom. At the upper end of the lower case 21, a flange 21c that overlaps the flange 22c is formed. The flange 21c is formed with boss portions 21b provided with holes 21a at three positions overlapping the flange 22c of the upper case 22, and the upper case 22 and the lower case 21 are secured by stopping the tapping screws 24 in the holes 21a. Are connected.

  The flange 22c of the upper case 22 has three mounting holes 22d. The lower case 21 has a mounting hole 21d at a position overlapping the mounting hole 22d. The linear drive device 1 can be attached to the partition wall 19 indicated by a one-dot chain line in FIG. 1B by the attachment holes 21d and 22d. Therefore, power is supplied from the first space 19a to the motor 9 among the two spaces partitioned by the partition wall 19, while various operations by the output member 3 are performed in the second space 19b having an atmosphere different from that of the first space 19a. be able to.

  In the case 2 thus formed, a motor mounting plate 90 is fixed to the bottom side of the lower case 21 with screws or the like, and the motor 9 is mounted on the motor mounting plate 90 with the rotary shaft 9a facing downward. It is attached. Here, since power supply to the motor 9 is performed from the outside, a power supply member (not shown) such as a flexible substrate for power supply to the motor 9 is drawn out through the lower case 21. A portion that penetrates the case 2 is sealed with potting resin or the like.

  Further, on the bottom side of the lower case 21, an annular protrusion 21g is formed inside the recess 21f, and the outer ring 141 of the ball bearing 14 is fixed inside the annular protrusion 21g. An inner ring 142 of a ball bearing 14 is fixed to the outside of the lower end side cylindrical portion of the driven pulley 10b, and the feed screw 6 is rotatably supported on the bottom surface side of the case 2 by the ball bearing 14. .

  In this manner, both ends of the feed screw 6 are rotatably held by the opposing portions of the case 2. In the case 2, both ends of the feed screw 6 are held by the ball bearing 14 disposed inside the lower case 21 and the bottomed circular recess 23 a formed in the upper case 22. There is no portion that penetrates the portion that holds both ends of 6. Accordingly, the inside of the case 2 is sealed except for the portion of the plate 23 in which the three through holes 23d are formed, and the first space 19a and the second space 19b are not communicated by the internal space of the case 2. The first space 19a and the second space 19b are in a sealed state.

(Operation of linear drive)
The linear drive device 1 operates as follows by the above-described configurations. First, by applying a predetermined drive signal to the motor 9 from an external drive device, the motor 9 rotates. The rotation of the motor 9 is transmitted to the feed screw 6 through the transmission mechanism 10. Then, the carriage 5 linearly moves in the direction of the axis L of the feed screw 6 based on the rotation of the feed screw 6. Since the carriage 5 is fixed integrally with the output member 3 via the connecting shaft 4, the carriage 5 and the output member 3 operate integrally. Therefore, the output member 3 moves linearly outside the case 2 based on the linear movement of the carriage 5.

  Meanwhile, in the linear drive device 1, the rotational speed of the feed screw 6 and the position of the carriage 5 are detected based on outputs from the rotation detection device 11 and the position detection device 12, and based on the detection result, the output member 3. The position can be detected. Therefore, the output member 3 can be moved to a desired position in the stroke at a desired timing by appropriately controlling the rotation direction, rotation speed, and rotation amount of the motor 9. Further, the carriage 5 is driven at a low speed near the bottom dead center (the lower end side of the feed screw 6) M and near the top dead center (the upper end side of the feed screw 6), and the carriage 5 is driven at a high speed in the intermediate region. It is also possible to perform control such as driving with.

(Main effects of this embodiment)
As described above, in the linear drive device 1 of this embodiment, when the movable body 7 is linearly driven by the feed screw 6, both ends of the feed screw 6 are rotatably held by the case 2. When the stroke of the movable body 7 is set to be long and the carriage 5 is located at any position on the feed screw 6, the feed screw 6 is not inclined or shaken. Therefore, the carriage 5 and the output member 3 can be stably operated.

  In addition, since both ends of the feed screw 6 are rotatably held by the case 2, the feed screw 6 can be lengthened, and members disposed in the middle portion of the feed screw 6 in the length direction can be minimized. Therefore, substantially the entire length of the feed screw 6 can be used as the movement range of the carriage 5 and the stroke of the movable body 7 can be easily set long.

  Further, since the carriage 5 and the output member 3 are connected by the three connecting shafts 4, it is possible to prevent the output member 3 from being inclined. Moreover, three connecting shafts 4 are arranged in parallel with the axis L of the feed screw 6 at positions surrounding the feed screw 6. For this reason, since the carriage 5 and the output member 3 are supported at three points, the inclination of the output member 3 can be reliably prevented, and the operation of the output member 3 can be stabilized. In addition, since the torsional rigidity of the movable body 7 with respect to the torsional force around the axis L of the feed screw 6 can be increased, the displacement of the output member 3 when the torsional force is applied to the movable body 7 can be suppressed. At the same time, the deformation and breakage of the movable body 7 can be prevented.

  In addition, since the belt mechanism is adopted as the transmission mechanism 10 that mechanically connects the motor 9 and the feed screw 6, it is possible to suppress the vibration on the motor 9 side from being transmitted to the feed screw 6 side. Therefore, the operations of the carriage 5 and the output member 3 can be stabilized.

  Furthermore, since the position information of the movable body 7 can be acquired based on the outputs from the rotation detection device 11 and the position detection device 12, the origin of the carriage 5 (output member 3) can be reliably detected. Further, since the position information of the movable body 7 can be acquired, control such as changing the driving speed according to the carriage 5 (the output member 3) is also possible. Therefore, depending on the use of the linear drive device 1, The output member 3 can be driven under optimum conditions.

  Furthermore, since the rotation preventing shaft 80 extending in parallel with the feed screw 6 and the connecting shaft 4 is used in configuring the follow-up preventing mechanism 8 for the carriage 5, the load applied to the connecting shaft 4 can be reduced.

(Another embodiment)
In the above embodiment, in the movable body 7, the carriage 5 and the output member 3 are connected by the three connecting shafts 4. However, the carriage 5 and the output member 3 are connected by one, two, or four or more connecting shafts 4. May be connected.

  In the above embodiment, the companion prevention mechanism 8 is configured using the rotation prevention shaft 80, but the companion prevention mechanism 8 may be configured using the inner peripheral surface of the case 2, and the connection shaft 4 is used. Accordingly, the attendant prevention mechanism 8 may be configured.

  In the above embodiment, a belt mechanism is used as the transmission mechanism 10, but a gear transmission mechanism may be employed depending on the application.

(A), (b) is the top view of the principal part of the drive mechanism of the linear drive device to which this invention is applied, and the longitudinal cross-sectional view of the said linear drive device. It is explanatory drawing which shows a mode that the movable body moved upwards in the linear drive device shown in FIG. It is a perspective view which shows a mode that the case was abbreviate | omitted from the linear drive device shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear drive device 2 Case 3 Output member 4 Connecting shaft 5 Carriage 6 Feed screw 7 Movable body 8 Accompanying prevention mechanism 9 Motor 10 Transmission mechanism 11 Rotation detection device 12 Position detection device 80 Rotation prevention shaft

Claims (6)

A motor, a feed screw that rotates around the axis based on the rotational drive of the motor, a movable body that engages with the feed screw and is linearly driven based on the rotation of the feed screw, and the feed screw rotates. In a linear drive device having a companion block mechanism for blocking the companion of the movable body at the time,
A case that accommodates the motor, the feed screw, and the companion prevention mechanism inside;
Both ends of the feed screw are rotatably held by the case,
The movable body includes a carriage that engages with the feed screw in the case and moves linearly on the feed screw, a connecting member that extends from the carriage through the case to the outside of the case, and the case And an output member coupled to the coupling member on the outside of the linear drive device.   The linear drive device according to claim 1, wherein the connecting member is three or more shaft bodies.   2. The linear drive device according to claim 1, wherein the connecting member is three or more shaft bodies extending in parallel with a central axis of the feed screw at a position surrounding the feed screw. The portion through which the connecting member penetrates in the case is a through hole that constitutes the outer periphery and sliding portion of the connecting member,
The linear drive device according to claim 3, wherein the inside and the outside of the case are sealed except for a surface forming the through hole. A transmission mechanism for transmitting rotation of the rotation shaft of the motor to the feed screw;
The transmission mechanism includes a drive pulley attached to a rotating shaft of the motor, a driven pulley attached to the feed screw, and a belt spanned on the drive pulley and the driven pulley. The linear drive device according to any one of claims 1 to 4.   6. The apparatus according to claim 1, further comprising at least one of a position detection unit that detects a position of the movable body and a rotation detection unit that detects a rotation amount of the feed screw. Linear drive device.

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