JP2009171708A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear actuator which has a shorter length relative to the movement amount of a motor shaft, can be manufactured at low costs and is extremely easily usable. <P>SOLUTION: The linear actuator includes a plurality of hollow coils secured to the interior of an outer cylinder and axially arranged, and a motor shaft disposed inside further than the hollow coils, to which a plurality of magnets arranged axially are secured, wherein the plurality of hollow coils are selectively excited to axially move the motor shaft to which the magnets are secured. The linear actuator further includes a motor part having the plurality of hollow coils arranged axially and the motor shaft to which the plurality of axially arranged magnets are secured, a guide part arranged in parallel with the motor shaft and having a guide shaft supported on both sides with slide bearings, and a connecting member connecting the ends of the guide shaft and the motor shaft. A movement amount detection device for detecting the movement amount of the guide shaft is disposed to the guide part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor in which a plurality of hollow coils fixed in the outer cylinder and arranged in the axial direction, and a plurality of magnets arranged in the axial direction and fixed in the hollow direction are fixed. And a linear actuator that moves the motor shaft in which the magnet is fixed in the axial direction by selectively exciting the plurality of hollow coils. The present invention also relates to a linear actuator that can move with high accuracy.

  A plurality of hollow coils that are fixed inside the outer cylinder and arranged in the axial direction, and a motor shaft that is arranged further inside the hollow coil and that has a plurality of magnets arranged in the axial direction fixed thereto. The linear actuator that moves the motor shaft to which the magnet is fixed in the axial direction by selectively exciting the plurality of hollow coils can move the motor shaft in the axial direction simply by providing a power source. Therefore, it can be used as a simple linear drive device. Furthermore, since the linear actuator can control the position of the motor shaft by providing the movement amount detection device, it can also be used as a linear motion drive device capable of higher movement control.

  Therefore, the linear actuator does not require a hydraulic device or a pneumatic device that is essential as a power source in other linear drive devices, for example, a hydraulic cylinder or an air cylinder. Since it can move in the axial direction, it can be suitably used even in a small-sized device that does not have a hydraulic device or a pneumatic device because no hydraulic cylinder or air cylinder is used. Since the position of the motor shaft can be controlled by providing the movement amount detection device, it is possible not only to position with a stopper like a hydraulic cylinder or an air cylinder but also to stop at an arbitrary position.

  However, the linear actuator according to the prior art has an inner portion of the outer cylinder 52 to which a plurality of hollow coils 51 arranged in the axial direction are fixed, as shown in FIG. 8 as an example of the linear actuator 50 according to the prior art. In addition, the motor shaft 54 to which a plurality of magnets 53 arranged in the axial direction is fixed is inserted, and the space between the hollow coil 51 of the outer cylinder 52 and the motor shaft 54 is considerably large. There was a gap, and the outer cylinder 52 and the motor shaft 54 were completely separable.

  Therefore, when used as a linear drive device, the motor shaft 54 is supported by a pair of support members 55 as shown in FIG. 9 as an example of a moving device using a linear actuator of the prior art. When the movable body 56 is moved by the outer cylinder 52 fitted around the motor shaft 54, the movable body 56 is supported by a pair of guide rails 57, 57 arranged in parallel to the motor shaft 54. It is necessary to fix the outer cylinder 52 to the movable body 56 supported by the guide rail 57 and move the movable body 56 by the outer cylinder 52. Therefore, it is necessary to use highly accurate and expensive parts such as the guide rail 57, and the number of parts is inevitably increased, and the outer cylinder 52 and the motor shaft 54 are high so that they do not contact each other during assembly. It had to be assembled with precision, and it had to be expensive.

  In order to eliminate this drawback, the present applicant has developed a linear actuator 60 configured to be easily used as shown in FIG. The linear actuator 60 has an outer cylinder 62 to which a plurality of hollow coils 61 arranged in the axial direction are fixed, and a plurality of magnets 63 arranged in the axial direction inside the hollow coil 61. A motor shaft 65 holding the outer sleeve 64 is inserted, and the motor shaft 65 is supported on both sides by a slide bearing 66 and a ball spline 67 so as not to rotate. A movement amount detection device 68 is arranged at the rear end (right side in FIG. 10) of the motor shaft 65, and has been filed as Patent Document 1.

  The linear actuator 60 does not rotate because the motor shaft 65 is non-rotatably supported by the ball spline 67, and the position can be detected and controlled by the movement amount detection device 68. Therefore, the linear actuator 60 advances and retreats with high accuracy. It is possible to use it at low cost because all the guide mechanisms such as guide rails are unnecessary, and only a power source is required, and no hydraulic device or pneumatic device is required. It can be used very simply instead of the air cylinder.

  However, in this linear actuator 60, a drive mechanism for the motor shaft 65 and a movement amount detection device 68 for detecting the position of the motor shaft 65 in the axial direction are arranged in series, and compared with the movement amount of the motor shaft 65. Then, the length of the linear actuator 60 is long, resulting in a result that cannot contribute to space saving as a whole.

  Further, in order to support the motor shaft 65 with the ball spline 67 in a non-rotatable manner, the outer sleeve 64 that wraps the outside of the motor shaft 65 requires sufficient strength and wear resistance. For the magnetic circuit formed between the magnet 61 and the magnet 63, the outer sleeve 64 must be a non-magnetic material. Therefore, the material of the outer sleeve 64 is extremely limited and difficult to process. Therefore, it was necessary to use materials that could not be manufactured at low cost.

Japanese Patent Application No. 2006-328202

  The object of the present invention is to solve such problems of the prior art, the length of the linear actuator is short with respect to the movement amount of the motor shaft, and it can contribute to space saving as a whole, and It can be manufactured at low cost without using special materials, and only a power source is required, and no hydraulic or pneumatic device is required. It can be used very easily instead of a hydraulic cylinder or air cylinder. It is to provide a linear actuator capable of

  In order to solve the above-described problems, the present invention provides a plurality of hollow coils fixed in the outer cylinder and arranged in the axial direction, and a plurality of hollow coils arranged further inside the hollow coil and arranged in the axial direction. A linear actuator that moves the motor shaft in which the magnet is fixed in the axial direction by selectively exciting the plurality of hollow coils. A motor unit having a plurality of arranged hollow coils, a motor shaft to which a plurality of magnets arranged in the axial direction are fixed, and arranged parallel to the motor shaft, both sides are supported by slide bearings. A guide portion having a guide shaft and a connecting member for connecting the end portion of the guide shaft and the motor shaft, and the guide portion detects the amount of movement of the guide shaft. There is provided a linear actuator, characterized in that a movement amount detector for.

  Here, it is preferable that the guide shaft is a single shaft and at least one of the slide bearings is a ball spline, or the guide shaft is two shafts arranged in parallel to each other, It is desirable that the slide bearing is a circulating or finite stroke axial moving roller bearing or an axial moving slide bearing.

  In addition, a vent hole is provided on the outer periphery of the hollow coil, and it is desirable to cool the motor part by passing air through the vent hole, and a fan is provided at at least one end of the vent hole. It is desirable to forcibly cool the vent hole with this fan. The movement amount detection device preferably includes a scale with a scale stamped on a transparent plate and a reading device arranged with the scale interposed therebetween, and the scale of the movement amount detection device further includes the guide shaft. In addition, it is desirable that the reader is attached to the main body.

  Since the linear actuator of the present invention is configured as described above, the length of the linear actuator is short with respect to the movement amount of the motor shaft, which can contribute to space saving as a whole, and a special material. Can be manufactured at low cost without using a hydraulic power source, and only a power source is required, a hydraulic device and a pneumatic device are unnecessary, and a linear that can be used very easily instead of a hydraulic cylinder or an air cylinder An actuator can be provided.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. 1 is a sectional view showing a linear actuator according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line AA in FIG. FIG.

  As shown in FIG. 1, a linear actuator 1 according to a first embodiment of the present invention is fixed inside an outer cylinder 3 held by a body 2 as an exterior member, and has a plurality of hollows arranged in an axial direction. The coil 4 and a motor shaft 6 disposed on the inner side of the hollow coil 4 and having a plurality of magnets 5 arranged in the axial direction are fixed. By exciting, the motor shaft 6 to which the magnet 5 is fixed is moved in the axial direction.

  The linear actuator 1 of this embodiment includes a motor unit 9 having a plurality of hollow coils 4 arranged in the axial direction and a motor shaft 6 to which a plurality of magnets 5 arranged in the axial direction are fixed. A guide portion 12 having a guide shaft 11 disposed in parallel to the motor shaft 6 and supported by slide bearings 10 on both sides, and a connecting member 13 for connecting the end portions of the guide shaft 11 and the motor shaft 6. is doing.

  The motor shaft 6 is arranged inside the hollow coil 4, and a plurality of magnets 5 arranged in the axial direction are inserted into the outer sleeve 8 through the spacer 7 and integrated, and the hollow coil 4 As described later, a slight gap is provided between the inner diameter of the outer sleeve 8 and the outer diameter of the outer sleeve 8. Since there is a slight gap between the outer sleeve 8 and the inner diameter of the hollow coil 4, the outer sleeve 8 does not move while in contact with the hollow coil 4, and therefore wear does not occur. Therefore, strength and wear resistance are necessary. However, any material can be used as long as it is simply a non-magnetic material.

  Accordingly, the outer sleeve 8 may be a tube made of a plastic film or the like, so that the hollow coil 4 and the magnet 5 are not in direct contact between the inner diameter of the hollow coil 4 and the outer diameter of the outer sleeve 8. The outer sleeve 8 can be omitted when there is no problem even if a sufficiently large gap is provided, or when there is no problem even if the hollow coil 4 and the magnet 5 are in direct contact.

  Further, the motor shaft 6 is made of a nonmagnetic material except for the magnet 5 so as not to affect the magnetic circuit formed between the hollow coil 4 and the magnet 5, and is appropriately selected from any nonmagnetic material. Can be used. For example, when strength or rigidity is required, a rod or pipe such as stainless steel or bronze is desirable, and when it is necessary to reduce the weight, it is desirable to employ aluminum or, in some cases, plastic.

  In this embodiment, the guide shaft 11 is a single shaft as shown in FIG. 1, and at least one of the slide bearings 10 supporting both ends, for example, the left slide bearing is used as a ball spline 10a. The guide shaft 11 is supported so as to be movable in the axial direction without rotating. For this reason, the motor shaft 6 whose end is connected to the guide shaft 11 by the connecting member 13 can move only in the axial direction without moving its center line in the lateral direction.

  The slide bearing 10 has no problem even if the ball splines 10a are provided at both ends, but it is sufficient to prevent the guide shaft 11 from rotating on one side. Since the mounting angle has to be adjusted so that the position of the shaft 11 and the spline groove coincide with each other, it is desirable that only one side be provided. The ball spline 10a is desirably a circulation ball spline in order to increase the movement stroke of the guide shaft 11.

  The slide bearing 10 may be either a sliding bearing or a roller bearing, but it is desirable to use a circulating or finite stroke axial moving roller bearing or an axial moving slide bearing. In the case of slide bearings, oil-impregnated bearings such as sintered oil-impregnated bearings and plastic bearings such as nylon and polycarbonate are used so that they can move with low friction resistance without lubrication. It is desirable.

  The non-rotatable guide shaft 11 and the motor shaft 6 are connected to each other by connecting members 13 provided at both ends, and the magnet 5 is formed by selectively exciting the plurality of hollow coils 4. The fixed motor shaft 6 moves in the axial direction, and the guide shaft 11 connected by the connecting member 13 can also move in the axial direction.

  Further, in this embodiment, a movement amount detection device 14 is disposed between the motor shaft 6 and the guide shaft 11. As shown in FIGS. 2 and 3, the movement amount detection device 14 includes a scale 15 fixed to the guide shaft 11, and a reading device 18 including a light source 16 and a light receiving element 17 fixed to the main body 2. When the motor shaft 6 is moved, the guide shaft 11 connected by the connecting member 13 is moved, and the scale 15 fixed to the guide shaft 11 is read by the reading device 18 fixed to the main body 2 to read the motor shaft 6. The current position in the axial direction is detected, and the amount of movement of the motor shaft 6 is detected.

  In this way, the movement amount detection device 14 of this embodiment detects the current position of the motor shaft 6 in the axial direction, stops the motor shaft 6 at an accurate position, or controls the movement of the motor shaft 6. Since the movement of the motor shaft 6 can be controlled with high accuracy and the movement amount detection device 14 is built in, it is necessary to provide a movement amount detection device for detecting the movement stroke on the moving body as in the prior art. This eliminates the need for space saving. Further, the movement amount detection device 14 is not limited to the movement amount detection device of the type exemplified here, and it is needless to say that any movement amount detection device can be adopted.

  In the embodiment shown in FIG. 2, the cylindrical motor shaft 6 is inserted inside the annular hollow coil 4. However, as in the modification shown in FIG. In this case, a square motor shaft 6 may be inserted. In this embodiment, the hollow coil 4 has an open shape on the right side, but it is needless to say that the closed shape can be used to enclose the square motor shaft 6 from the periphery. .

  As described above, the linear actuator 1 of this embodiment includes the plurality of hollow coils 4 arranged in the axial direction and the motor shaft 6 to which the plurality of magnets 5 arranged in the axial direction are fixed. And a guide portion 12 having a guide shaft 11 arranged in parallel to the motor shaft 6 and supported by slide bearings 10 on both sides, and a connection for connecting the end portions of the guide shaft 11 and the motor shaft 6. Since the movement amount detection device 14 for detecting the movement amount of the motor shaft 6 is arranged on the guide shaft 11, the length of the linear actuator is short with respect to the movement amount of the motor shaft. It can save space, can be manufactured at low cost without using special materials, requires only a power source, and does not require a hydraulic device or pneumatic device. It is possible to provide a linear actuator which can be extremely conveniently used in place of Sunda or an air cylinder.

  4 is a sectional view showing a linear actuator according to a second embodiment of the present invention, FIG. 5 is a plan view, FIG. 6 is a bottom view, and FIG. 7 is a sectional view taken along line BB in FIG. The linear actuator 20 of this embodiment has substantially the same configuration as that of the linear actuator 1 of the first embodiment. As shown in the figure, the linear actuator 20 is disposed inside an outer cylinder 22 held by a main body 21 that is an exterior member. A plurality of hollow coils 23 that are fixed and arranged in the axial direction, and a motor shaft 25 that is arranged further inside the hollow coils 23 and that has a plurality of magnets 24 that are arranged in the axial direction and fixed thereto; By selectively exciting the plurality of hollow coils 23, the motor shaft 25 to which the magnet 24 is fixed is moved in the axial direction.

  The linear actuator 20 of the second embodiment includes a motor unit having a plurality of hollow coils 23 arranged in the axial direction and a motor shaft 25 to which a plurality of magnets 24 arranged in the axial direction are fixed. 26, a guide portion 28 having a guide shaft 27 arranged in parallel to the motor shaft 25 and supported at both ends by slide bearings (not shown), and a connection for connecting the end portions of the guide shaft 27 and the motor shaft 25 Member 29.

  The motor shaft 25 is arranged inside the hollow coil 23, and a plurality of magnets 24 arranged in the axial direction are integrated into the outer sleeve 31 via the spacer 30. As described later, a slight gap is provided between the inner diameter of the outer sleeve 31 and the outer diameter of the outer sleeve 31. Since there is a slight gap between the outer sleeve 31 and the inner diameter of the hollow coil 23, the outer sleeve 31 does not move while in contact with the hollow coil 23, and therefore no wear occurs, so strength and wear resistance are necessary. However, any material can be used as long as it is simply a non-magnetic material.

  Accordingly, the outer sleeve 31 may be a tube made of a plastic film, and the hollow coil 23 and the magnet 24 are not in direct contact between the inner diameter of the hollow coil 23 and the outer diameter of the outer sleeve 31. The outer sleeve 31 can be omitted when there is no problem even if a sufficiently large gap is provided, or when there is no problem even if the hollow coil 23 and the magnet 24 are in direct contact.

  In addition, the motor shaft 25 is made of a nonmagnetic material except for the magnet 24 so as not to affect the magnetic circuit formed between the hollow coil 23 and the magnet 24, and is appropriately selected from any nonmagnetic material. Can be used. For example, when strength and rigidity are required, rods and pipes such as stainless steel and bronze are desirable. When it is necessary to reduce the weight, it is desirable to employ aluminum or, in some cases, plastic.

  In this embodiment, as shown in FIG. 7, the guide shaft 27 employs two shafts arranged in parallel to each other. For this reason, when the two guide shafts 27 are connected to each other by the connecting member 29, they are supported so as to be movable only in the axial direction without rotating, and the motor shaft 25 connected by the connecting member 29 is also in the axial direction. Can only move. Therefore, the slide bearing (not shown) for supporting both ends of the guide shaft 27 does not need to use a ball spline, and is a circular or finite stroke axial moving roller bearing or an axial moving slide bearing. Is desirable.

  The slide bearing (not shown) may be either a sliding bearing or a rolling bearing, but it is desirable to use a circulating or finite stroke axial moving roller bearing or an axial moving slide bearing. . In the case of slide bearings, oil-impregnated bearings such as sintered oil-impregnated bearings and plastic bearings such as nylon and polycarbonate are used so that they can move with low friction resistance without lubrication. It is desirable.

  In the linear actuator 20 of the present embodiment, cooling air is passed through the outer periphery of the hollow coil 23 in order to prevent the motor portion 26 from generating excessive heat. That is, the outer side of the hollow coil 23 of the present embodiment is held by the outer cylinder 22 having a cross-sectional shape shown in FIG. 7, and the main body 21 is formed by forming the vent hole 22a along the axial direction of the outer cylinder 22. The outer periphery of the hollow coil 23 is cooled by passing cooling air between the outer cylinder 22 and the outer cylinder 22.

  As shown in FIG. 5, an air supply fan 32 and an exhaust fan 33 are arranged on the upper surface of the main body 21 at the end of the air vent 22 a, and the fans 32 and 33 cool the air vent 22 a. The motor section 26 is forcibly cooled through the air for use. Both of these fans 32 and 33 are not necessarily required, and either one of the air supply fan and the exhaust fan is sufficient in many cases. It can also be cooling by.

  In this embodiment, as described above, the two guide shafts 27 and the motor shaft 25 are connected by the connecting members 29 provided at both ends, and the plurality of hollow coils 23 are selectively excited. Thus, the motor shaft 25 to which the magnet 24 is fixed moves in the axial direction, and the guide shaft 27 connected by the connecting member 29 can also move in the axial direction.

  A movement amount detection device 34 that detects the movement amount of the guide shaft 27 is disposed between the two guide shafts 27 constituting the guide portion 28. As shown in FIGS. 6 and 7, the movement amount detection device 34 includes a reading device 36 fixed to the main body 21 and a scale 35 fixed to the guide shaft 27, and has a scale on the transparent plate. On both sides of the scale 35 that is imprinted and fixed to the guide shaft 27, a reading device 36 that includes a light source 37 and a light receiving element 38 that are respectively fixed to the main body 21 with the scale 35 interposed therebetween is disposed.

  When the motor shaft 25 is moved, the guide shaft 27 connected by the connecting member 29 is moved. The scale of the scale 35 fixed to the guide shaft 27 is read by the reading device 36 fixed to the main body 21 and the motor shaft 25 is moved. The current position in the axial direction is detected, and the amount of movement of the motor shaft 25 is detected.

  In this way, the movement amount detection device 34 of this embodiment detects the current position of the motor shaft 25 in the axial direction, stops the motor shaft 25 at an accurate position, or controls the movement of the motor shaft 25. Since the movement of the motor shaft 25 can be controlled with high accuracy and the movement amount detection device 34 is built in, it is necessary to provide a movement amount detection device for detecting movement on the object to be moved as in the prior art. This eliminates the need for space saving. The movement amount detection device 34 is not limited to the movement amount detection device of the type exemplified here, and it is needless to say that any movement amount detection device can be adopted.

  As described above, the linear actuator 20 of this embodiment includes a plurality of hollow coils 23 arranged in the axial direction and a motor shaft 25 to which a plurality of magnets 24 arranged in the axial direction are fixed. A motor part 26 having a guide part 28 having two guide shafts 27 arranged parallel to the motor shaft 25 and supported on both sides by slide bearings (not shown), and the guide shaft 27 and the motor shaft 25. Since the movement amount detecting device 34 for detecting the movement amount of the guide shaft 27 is disposed in the guide portion 28, the length of the linear actuator with respect to the movement amount of the motor shaft is provided. It is short and can save space as a whole, can be manufactured at low cost without using special materials, requires only a power source, And pneumatic devices is not required, it is possible to provide a linear actuator which can be extremely conveniently used in place of the hydraulic cylinder or an air cylinder.

It is sectional drawing which shows the linear actuator of 1st Example of this invention. It is the sectional view on the AA line of FIG. It is the sectional view on the AA line of FIG. 1 which shows the other embodiment of FIG. It is sectional drawing which shows the linear actuator of 2nd Example of this invention. It is a top view which shows the linear actuator of 2nd Example of this invention. It is a bottom view which shows the linear actuator of 2nd Example of this invention. It is the BB sectional view taken on the line of FIG. It is sectional drawing which shows an example of the linear actuator of a prior art. It is a perspective view which shows an example of the moving apparatus using this linear actuator. It is sectional drawing of the linear actuator of the prior art comprised so that it could use simply, which the present applicant developed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20 Linear actuator 2,21 Main body 3,22 Outer cylinder 22a Vent hole 4,23 Hollow coil 5,24 Magnet 6,25 Motor shaft 7,30 Spacer 8,31 Outer sleeve 9,26 Motor part 10 Slide bearing 10a Ball Spline 11, 27 Guide shaft 12, 28 Guide portion 13, 29 Connecting member 14, 34 Movement detection device 15, 35 Scale 18, 36 Reading device 32, 33 Fan 16, 37 Light source 17, 38 Light receiving element

Claims (7)

A plurality of hollow coils that are fixed inside the outer cylinder and arranged in the axial direction, and a motor shaft that is arranged further inside the hollow coil and that has a plurality of magnets arranged in the axial direction fixed thereto. In the linear actuator that moves the motor shaft in which the magnet is fixed in the axial direction by selectively exciting the plurality of hollow coils,
A motor unit having a plurality of hollow coils arranged in the axial direction and a motor shaft to which a plurality of magnets arranged in the axial direction are fixed;
A guide portion disposed in parallel with the motor shaft and having a guide shaft supported on both sides by slide bearings;
A connecting member that connects ends of the guide shaft and the motor shaft;
A linear actuator, wherein a movement amount detection device for detecting a movement amount of the guide shaft is disposed in the guide portion.   The linear actuator according to claim 1, wherein the guide shaft is a single shaft, and at least one of the slide bearings is a ball spline.   The guide shaft is two shafts arranged in parallel to each other, and the slide bearing is a circular or finite stroke axial moving roller bearing or an axial moving slide bearing. Item 10. The linear actuator according to Item 1.   The linear actuator according to any one of claims 1 to 3, wherein a vent hole is provided on an outer periphery of the hollow coil, and the motor unit is cooled by passing air through the vent hole.   The linear actuator according to claim 4, wherein a fan is provided at at least one end of the vent hole, and the fan is forcibly cooled by passing air through the vent hole.   The said movement amount detection apparatus consists of the scale by which the scale was engraved on the transparent plate, and the reader device arrange | positioned on both sides of this scale, The Claim 1 thru | or 5 characterized by the above-mentioned. Linear actuator.   The linear actuator according to claim 6, wherein a scale of the movement amount detection device is attached to the guide shaft, and the reading device is attached to a main body.

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